Science Demonstration (30 points) - Rubric is located @ http://www.jhargis.com/demo3310r.htm, an acceptable student example can be found at http://www.jhargis.com/demoex.htm and for historical student FAQs, please refer to http://www.jhargis.com/demofaq.htm. 

After viewing the instructor model a demonstration, each person will be assigned one of the brief descriptions of a science experiment demonstration listed below.  Each student will read, understand, gather the materials, practice and home and present their demonstration in class (highly recommended that you actively observe your colleagues demonstrations, you may wish to use one of them during one of your conceptual teaching microTeaches in one of the elementary classrooms to 'real-live' students).  The demo will be brief, typically between 2-5 minutes and incredibly engaging and exciting!  Finally, you will summarize your experience in a 1-2 page paper and include the criteria in the rubric at http://www.jhargis.com/demo3310r.htm.  (summary sheet located at DemSum)

Remember:
Avoid putting children in danger
Model proper skills
Focus on a concept
Raise interest, questions, and problems

Effective Demonstrations
Have a clear purpose
Need to be thought through and carefully planned
Practice the demonstration
Safely involve the students in the demonstration
Use effective questions
Help focus attention and make connections
Use simple and familiar materials
Are visible to the students
Connect the demonstration to the objectives and standards

Student Demonstration Procedures:

1. Demonstrate Inertia (resistance to change in motion), a Property of Matter (anything that takes up space)

Materials:  Index Card; Nickel; Drinking Glass

Procedure: Lay the index card over the mouth of the glass;  Place the coin on top of the card centered over the mouth of the glass;  Flick or push the card quickly with your finger off of the glass.  The card should move forward and the coin drops into the glass. 
Lesson: The stationary card and coin are said to be at rest.   They remain motionless because of their inertia.  When the card is snapped, it slips under the stationary coin.  Gravity pulls the coin down into the glass.

Student Critique:  I liked the demonstration that is mentioned above.  It was very simple and the materials were very inexpensive and easy to gather.  The only thing I would suggest is that when picking out a drinking glass, make sure the drinking glass is clear and not colored.  Also be sure that the circumference of the drinking glass should be large enough that the index will comfortably fit on the top.  My experiment worked well but the demonstration was very quick.   My suggestion would be to videotape the actual demonstration so you can show the class what happens in slow motion. (73% of a students who observed this demo indicated they would use it in their class)

2. Atomic Charges
Materials: Piece of notebook paper; paper hole punch; balloon.

Procedure: Use the hole punch to cut 15 to 20 small circles from the piece of paper; Separate the circles and spread them on a table;  Inflate the balloon and tie it; Rub the balloon against your hair;  Hold the balloon close to, but not touching, the paper circles.  The paper circles will hop up and stick to the balloon.

Lesson:  Paper is an example of matter, and all matter is made up of atoms.  Each atom has a positive center with negatively charged electrons spinning around the outside.  The balloon rubs the electrons off of the hair, giving the balloon an excess of negative charges.  The positive part of the paper circles is attracted to the excessive negative charge on the balloon.  This attraction between the positive and negative charge is great enough to overcome the force of gravity, and the circles will hop upward toward the balloon.

Student Critique: I think this would be a very good introduction to this concept.  It demonstrates the concepts very well and quickly, which will help students assign meaning to it.  The materials are inexpensive and easy to obtain, to make it most cost effective. (81%)

3. Molecules
Materials: Dark food coloring; Tall, one-half pint jar of water.
Procedure:   Place the jar of water where it will not be moved or touched for 24 hours; Hold the food coloring container above the water and allow 2 drops to fall into the water; Observe immediately and then again in 24 hours.   The drops sink to the bottom forming colored streaks as they fall.  After 24 hours, the water is evenly colored.

Lesson: The atoms and molecules that make up matter are in constant motion.  Though not seen by the naked eye, water molecules are moving.  The small particles of food coloring are being pushed and shoved around by the moving water molecules.  Given enough time, the colored particles will evenly spread throughout the jar of vibrating water.  The movement is called diffusion.

Student Critique:   In general, I would rate this experiment a 10 across the board.  It was very easy to gather the materials needed to perform the experiment with little to no cost involved.  The experiment did work when I demonstrated it to the class and I would highly recommended this to other teachers if they were interested in demonstrating the concept diffusion. (81%)

4. Space and Matter
Materials: Glass liter jar, large mouth with lid; small ball or whole walnut; 500 mL uncooked rice.
Procedure: Fill the jar with uncooked rice;  Put the ball inside the  jar and close the lid;  Hold the jar upright, then turn it over to cover the ball; Shake the jar back and forth vigorously until the ball surfaces - do not shake up and down.  The ball comes to the surface.

Lesson:  There are spaces between the grains of rice.  As the jar is shaken, the rice gets closer together.  This is referred to as settling.   As the rice moves together, it pushes the ball upward.  Two pieces of matter cannot occupy the same spaces at the same time; thus the ball is moved by the packing together of rice grains.

Student Critique: Ease of gathering materials:  This experiment was very easy to do.  I had all my materials at home already.  I didn't have to spend anything for this experiment.  Did this work?...YES  It worked very well.  It took a while to get the ball to surface the first few times, but I finally got good at it.   I would definitely recommend this experiment to teach this concept. (66%)

5. Dry Paper - gases take up space.
Materials: clear drinking glass, 350 mL; piece of notebook paper; bucket (taller than the glass)

Procedure: Fill the bucket half full with water; wad the paper into a ball and push it to the bottom of the glass; turn the glass upside down - the paper wad must remain against the bottom; hold the glass vertically with its mouth pointing down; push the glass straight down into the bucket with water. DO NOT TILT. Remove the glass, remove the paper and examine. It should be dry.

Lesson:  The glass is filled with paper and air. The air prevents the water from entering the glass, thus keeping the paper dry.

Student Critique:  My experiment was relatively easy to perform.  It was not complicated and I feel that it is easy for even young children to perform this experiment.  The materials involved all are materials that I had at home, so it did not cost anything to do the experiment.   However if I would have had to purchase any materials, it would have only been a bucket and they are not costly.  I would recommend doing this experiment in a classroom with students. (81%)

6. Density - float an egg
Materials: 2 clear plastic cups; 5 mL table salt; 2 small uncooked eggs; 5 mL milk.

Procedure: Fill both cups 3/4 full with potable water; add the milk to one cup of potable water; add and stir the salt to the second cup of water; place an egg in each cup. The egg should float in the salt solution, but sinks in the milk solution. (if not, add more salt)

Lesson:  The milk was added only to give the water a cloudy appearance. The egg floats because it is not as heavy as the salty water. The heavy salt water is able to hold the egg up. The egg in the milky water is heavier than the water; thus it sinks.

Student Critique:  The cost of this project was very low.  You can find most of the items already in your home.  I would recommend this demonstration to others.  It definitely got the point across and the children can have fun doing it.  The experiment worked very well and I would highly rate it. (96%)

7. Capillary Action
Materials:1-2 stalks of fresh celery with leaves; red or blue food coloring; 1 clear drinking glass; knife.

Procedure: Fill the glass about 1/4 full with water; make a dark red or blue solution by adding food coloring to the water; cut across the bottom end of the celery stalk with a knife; stand the cut end of the celery in the colored water; after 24 hours observe the color of the leaves - they should be red or blue.

Lesson:  All plants have tiny tubes in their stalks. The colored water moves up through these tubes to the leaves. The water is pushed upward by the air pressure in the room. The pressure inside is less than outside the tubes; thus, the colored water is pushed up to the leaves. The movement of water up through tiny tubes is called capillary action.

Student Critique: This is an easy to do experiment using materials most people have available.  It can be challenging finding celery with leaves at the grocery store, however.  Two things I would add to the experiment are a control (celery in clear water) and cutting the experimental celery to see the path of the food coloring through the vegetable. (100%)

8. Gas Saturated Solutions
Materials: Small glass jar (possibly baby food jar); clear carbonated beverage; red food coloring.

Procedure: Fill the small glass jar 1/2 full with the beverage; add a few drops of food coloring; set the jar on a table and observe the liquid. Small bubbles of gas continuously rise to the top of the liquid.

Lesson:  Carbonated beverages are made by dissolving large amounts of carbon dioxide (CO₂) in flavored water. This excess amount of CO₂ is able to stay in the liquid because it is pushed with high pressure into the bottle and the bottle is immediately sealed. The bubbles that are rising in the cola are escaping CO₂.

Student Critique: The materials used were easy to find in my grocery store, and the cost was minimal.  In fact most people have them around their home.  The experiment worked well every time I performed it.  I would add on to the experiment by letting the water sit over night and conduct  follow-up observations.  I would also follow this activity with another activity to provide more than one example of the concept.  I would also utilize a video or a field trip to a bottling plant to observe the procedure first hand. (40%)

9. Oxidation
Materials: Apple; vitamin C tablet

Procedure: Cut the unpeeled apple in half; Crush the vitamin C tablet and sprinkle the powder over the cut surface of one of the apple halves; allow both apple sections to set uncovered for one hour; observe the color of each section. The untreated apple turns brown, but the section with the vitamin C is unchanged. NOTE: begin this demo at the beginning of the class period and return to the apple just before class is over.

Lesson:  Fruits discolor when bruised or peeled and exposed to air. This discoloration is caused by the breaking of cells. The chemicals released by the damaged cells react with oxygen resulting in changes in the fruit. Rapid color and taste changes occur because of the reaction with oxygen. Vitamin C prevents the darkening by reacting with the oxygen before it can combine with the released chemicals.

Student Critique: I think this would be a very good introduction to this concept.  It demonstrates the concepts very well and quickly, which will help students assign meaning to it.  The materials are inexpensive and easy to obtain, to make it most cost effective I would suggest cutting the apply into more than two pieces so you didn't need so many.  I would recommend this to others to use. (77%)

10. Chemical Reaction
Materials: Red food coloring; bleach; eyedropper; small glass jar (baby food jar).

Procedure: Fill the jar 1/2 full with water; add 2 drops of food coloring to the water and stir; use the eyedropper to add 1 drop of bleach to the colored water; add drops of bleach until the red solution turns clear; now add a drop of red food coloring to the clear liquid. The red water solution turns clear as the bleach moves down through it. Adding the red coloring to the clear solution containing the bleach produces an interesting effect in that the red dye disappears when it hits the liquid.

Lesson:  Bleach contains a chemical called sodium hypochloridite. This chemical contains oxygen that is easily released. Oxygen combines with the chemicals in dyes to form a colorless compound. The bleach decolorizes the red water as it moves downward. The red drop disappears because it is surrounded by bleach which decolorizes the red dye.

Student Critique 1: Interesting experiment, easy to get students to participate and peak their curiosity.  Good lesson for them to practice predicting skills.   Materials were also cheap and readily available around the teacher's house, which will make it easy for teachers to replicate.  This whole assignment is worthwhile - gave me good ideas for other experiments besides mine for me future classroom.   

Student Critique 2: I feel this experiment is good yet I did not like it b/c I dislike bleach.  The same experiment can be performed using an oxygen bleach (such as Shaklee's Nature Bright--a powered formula, so smell, no skin irritation).  My experiment was successful and showed the results it should have.  I would like to have expanded this experiment.  (Using hot, warm, and cold water) (different colors of dye). Bleach vs. oxygen bleach.  The cost is very inexpensive --cost of food coloring and bleach (under $1.00). (92%)

11. Oxygen Production
Materials: Hydrogen peroxide (H₂O₂); raw potato; 150 mL paper cup; knife.

Procedure: Fill the paper cup 1/2 full with hydrogen peroxide; add a slice of raw potato to the cup; observe the results - look specifically for bubbles of gas.

Lesson:  Raw potatoes contain the enzyme catalase. Enzymes are chemicals found in living cells. Their purpose is to speed up the breakdown of complex food chemicals into smaller, simpler, more usable parts. Catalase from the potato's cells causes the hydrogen peroxide to quickly break apart into water and oxygen gas.

Student Critique 1: My experiment was on the enzymes, using the potato and peroxide. I thought my experiment went well because it actually worked compared to some others that didn't. It only cost about three dollars and it is something that I think kids would be able to learn from. I recommend it for a class setting in groups because I think the students can learn from it.

Student Critique 2: The cost of this experiment was nothing for me because I had all the items in my house.  If I had not had all the items, I think that it would have been less than $5.00.  I thinks it was very simple to do.  In a large group (with my students it was difficult to really see what was happening.)   The students liked the experiment. The experiment worked fine.  I think in some ways the concept was difficult for my first graders, so this was probably intended for an older group. Overall, the experiment was interesting. My students thought something was going to explode.(35%)

12. Magnesium Hydroxide
Materials: 3 mL Epsom salt; 6 mL household ammonia; 1 small glass jar (possibly baby food jar)

Procedure: Fill the jar 1/2 full with water; stir 3 mL of Epsom salt into the water; pour 6 mL of ammonia into the jar - DO NOT STIR; allow the solution to stand for 5 minutes. A white, milky substance forms as the ammonia mixes with the Epsom salt solution. NOTE: In class, you will begin this, then another will present while you are waiting your 5 minutes, then you will step back in and finish.

Lesson:  Household ammonia's chemical name is ammonium hydroxide. Magnesium sulfate is the chemical name for Epsom salt. Mixing ammonia and Epsom salt causes a reaction which produces magnesium hydroxide as one of the products. Magnesium hydroxide is a white substance that does not dissolve well in water. After standing awhile, the white floating particles settle to the bottom of the jar. Magnesium hydroxide is part of the medicine called Milk of Magnesia.

Student Critique: This demonstration involves inexpensive, easy to gather materials (in other words, common household materials available at the grocery store at very low cost).  It works as intended, though the results will be more striking if allowed to sit overnight.  I recommend it for meeting Sunshine State Standards benchmarks (3rd grade SC.A.1.2.4, SC.H.1.2.1, SC.H.1.2.2, SC.E.1.2.1, SC.H.1.2.3, SC.H.1.2.4, MA.B.2.2.2, MA.B.4.2.1, and MA.B.4.2.2). (40%)

13. Organic Aromatic Compounds
Materials: Small glass jar (possibly baby food jar); rubbing alcohol; 15 whole cloves.

Procedure: Place the whole cloves in the jar; fill the jar 1/2 full with the alcohol; secure the lid and allow the jar to set for 7 days - NOTE: do this 7 days prior to your presentation - use your finger and dab a few drops of the alcohol solution onto a piece of paper; allow the alcohol to evaporate, then observe the scent on the paper. The paper has a faint, spicy, smell.

Lesson:  The alcohol dissolves the aromatic oil in the cloves. When the alcohol evaporates from the wrist, the scented oil is left on the skin. Perfumes are made by dissolving oils from flowers and other organic aromatic materials in alcohol.

Student Critique: Ease of gathering materials: I had to buy alcohol, baby food (for the jars,) and a jar of whole cloves, which cost $7!!! ( Pretty costly unless there is some other use for cloves.)  I would assume, however, that a classroom would already have alcohol and jars so therefore the ease of gathering materials in a classroom setting would be relatively easy... the jar of cloves would be used up if each individual in the class did the experiment.  The experiment worked very well, it was easy to demonstrate, made it easy to get the point across.  Overall, it demonstrated the concept in an interesting easy manner that would be useful for students. (92%)

14. Volume and Matter
Materials: Clear drinking glass, 350 mL; 6 marbles or rocks; masking tape.

Procedure: Fill 1/2 of the glass with water; use a piece of tape to mark the top of the water level; very carefully add the marbles or rocks to the water by tilting the glass and allowing one marble at a time to slide down the inside to the bottom; set the glass upright and notice the water level. The water level is higher with the marbles in the glass.

Lesson:  Water and marbles are both examples of matter. Two pieces of matter cannot occupy the same space at the same time. When the marbles are dropped in the jar, the water is pushed out of the way by the marbles. The rise in the water level is equal to the volume of the marbles.

Student Critique:  I think this was a great experiment.  Gathering the materials would be fun for this experiment.  I used rocks I found in Scotland.  I think we could go on a little field trip to find rocks.   The materials were inexpensive as well.  I only needed water, rocks and a twelve ounce glass.  The experiment worked and it will always work.  I would recommend this experiment to any teacher; it is very fun.  I would use this experiment to show why two matters take up their own space and one cannot take up the others' space. (50%)

15. Molecular Forces
Materials: 3 toothpicks; liquid dish soap; quart glass bowl.

Procedure: Fill the bowl 3/4 full with water; place the toothpicks side by side on the surface in the center of the water; treat the third toothpick by dipping its point in liquid detergent - use only a small amount - touch the treated toothpick tip between the floating sticks. The sticks quickly move away from each other.

Lesson:  The surface of water acts as if a thin skin were stretched across it. This allows objects to float on top. Detergent breaks the attraction between molecules where it touches, causing the water molecules to move outward and taking the floating sticks with them. This outward movement occurs because the water molecules are pulling on each other. It is almost as if the molecules are all playing tug of war and any break causes the "tuggers" to fall backwards.

Student Critique: I felt that this was a good experiment.  It gave meaning to the term "Molecular Forces" (by giving concrete examples the children can relate to, like the skin on the surface of the water). My experiment did not work due to some controllable variables. Be sure to have a very flat surface so the toothpicks do not float to one side of the container (which is what happened in my experiment), make sure there is enough detergent on the toothpick so the toothpicks split apart.  My experiment was inexpensive and would be beneficial to do in groups. (92%)

16. Dihydrogen Oxide Polarity
Materials: 1/3 meter sheet of wax paper; toothpick; eyedropper; water.

Procedure: Spread the wax paper on a table; use the eyedropper to position 3 or 4 separate small drops of water on the paper; wet the toothpick with water; bring the tip of the wet pick near, but not touching, one of the water drops. Repeat with the other drops. The drop should move toward the toothpick.

Lesson:  Water molecules have an attraction for each other. This attraction is strong enough to cause the water drop to move toward the water on the toothpick. The attraction of the water molecules for each other is due to the fact that each molecule has a positive and negative side. The positive side of one molecule attracts the negative side of another molecule.

Student Critique: This was a very inexpensive project to perform.  All of the materials were readily available.  I would not recommend this experiment because it did not work for me.  The water would only move toward the toothpick when touched.   When the toothpick was placed very near, yet not touching the water, no movement occurred. (62%)

17. Gravity and Immiscible Fluids
Materials: Clear drinking glass; 100 mL rubbing alcohol; 100 mL potable water; liquid cooking oil; eyedropper.

Procedure: Pour 100 mL of water into the glass; tilt the glass and very slowly pour in 100 mL alcohol - Be careful not to shake the glass because the alcohol and water will mix - fill the eyedropper with the cooking oil; place the tip of the dropper below the surface of the top alcohol layer and squeeze out several drops of oil. The alcohol forms a layer on top of the water. The drops of oil form perfect spheres that float in the center below the alcohol and on top of the water.

Lesson: Alcohol is lighter and will float on the water if the two are combined very carefully. Shaking causes them to mix, forming one solution. The oil is heavier than alcohol but lighter than water; thus the oil drops float between the two liquids. Gravity does not affect the drops because they are surrounded by liquid molecules that are pulling equally on them in all directions. The oil molecules pull on each other, forming a shape that takes up the least surface area, a sphere.

Student Critique: This experiment had hardly any expenses.  The following materials :  a glass, water, alcohol, medicine dropper, cooking oil, are all things that could be found in the house.  This experiment was easy to do, but must be done carefully in order for the correct results to occur.  I would use this experiment in my class.  I think kids would find it interesting and appealing to look at because the cooking oil just rests in between the water and alcohol and makes cool little spheres. (88%)

18. Fulcrum of levers and lifting ability

Materials:  three rulers, two matchboxes, and @20-25 washers or quarters.
Procedure: using tape tape two of the rulers together to make a "V".

Tape or glue two empty matchboxes (inner part) onto each end of the remaining ruler.  using the "V" ruler as the fulcrum place the other ruler on top with the center of the ruler (18 cm) being on the fulcrum. Place 4 washers in one matchbox and see how many washers would be required to lift the four washer. Repeat the exercise with the fulcrum at different points on the ruler. see how many quarters required to lift in each position

Lesson: the closer the fulcrum in to the load in a class one lever the less force required to lift it.

Student Critique: I liked the experiment. The materials were very easy to get and didn't cost a lot and should be found in any classroom.  Since it was very easy to see that more quarters were required as the fulcrum  moved away from the load more washers were required. and vis-a-versa. The experiment was also very easy to set up. (65%)

19. Splitting the Smartie
Equipment:
1. Filter paper or blotting paper  2. Tube of smarties  (or feel free to bring some for all of us) 3. Small cup of water   4. Plate

How to do the experiment:
1. Cut the blotting paper into circles about 15 cm across.
2. Place the plate on a flat surface and the paper on the plate.
3. Place a Smartie in the center of the paper.
4. Dip your finger into the water and hold it above the Smartie allowing a little water to rip onto the sweet.
5. Repeat fairly slowly until the sweet is quite wet and the circle of water on the blotting paper is about 5 cm across.
6. Leave.
7. In a little while you should be able to see rings of color round the Smartie.

Explanation:
The color in the sugar coating of the Smartie shell dissolves in the water. The water is drawn out through the paper by capillary action and moves in a growing circle. The different inks which make up the Smartie color move at different speeds and so they are separated.

At the 'molecular level' smaller hydrophilic molecules migrate faster through the paper. Hydrophilic means a "water-loving" substance, as opposed to hydrophobic compounds which are not soluble in water. Cooking oil is an example of a hydrophic substance. The colors that migrate the furthest from the candy have less of a mass than the ones closest to the candy.

Student Critique: This experiment did not go so well.  Ideally, this would be something that the students could do at home.  It did not cost very much and did not take a long time  to to complete, but it was hard to actually see the lines on the paper.  You might try coffee filters. (31%)

20. Iron in Cereal
A small magnet is used to remove particles of iron from common breakfast cereal.
You will need Total® brand cereal, or other high iron content breakfast cereal, mixing bowl, plastic or glass rod, large spoon, magnet.

Instructions:
Place the entire contents of a box of flakes into a large bowl. Use your hands to crush the flakes to pin-head size pieces. Add water and stir. Use additional water to keep the mixture thin and soupy. Tape a small magnet on the end of the glass rod. Stir the cereal soup with the magnet for several minutes. Small bits of pure iron will collect on the magnet!

Content:
The human body requires iron for many functions. Most importantly, iron is used in the production of hemoglobin molecules in red blood cells. It is the iron in the hemoglobin that attracts oxygen molecules, allowing the blood cells to carry oxygen to body cells. Red blood cells are constantly being replaced. Therefore, there is a constant need for a new supply of iron in the diet. That is why iron is often mentioned as a healthful additive to certain foods and vitamin pills.

The iron in the cereal is pure iron! Really! It is the same iron found in nails and automobiles. It is mixed in the cereal batter along with many other additives. The very tiny particles of iron quickly react with hydrochloric acid and other chemicals in the digestive tract, changing to a form easily absorbed by the body.

Student Critique: My experiment was on Iron in Cereal and I really felt like the experiment went well.  This would be something that the students could do at home and then bring in and discuss.  It did not cost very much and did not take a long time  to to complete.  I feel it would be interesting to the students.  You also might try this without the water, simply dry.  I found I could gather more iron on my magnet and it was less messy. (38%)

21. Nickel Karate
A spatula is used to eject the bottom coin from a tall stack of coins, using inertia and friction.

Standards:
Employ simple equipment and tools to gather data and extend the senses (Standard A.1.3).  The position of an object can be described by locating it relative to another object or the background (Standard B.2.1).  An object's motion can be described by tracing and measuring its position over time (Standard B.2.2).

You will need: 10 to 12 nickels, quarters or metal washers, spatula or thin butter knife, smooth table top

Instructions:
Place the stack of coins near the edge of a smooth topped table or other smooth surface. Hold the spatula blade flat against the smooth surface. With a quick flick of the wrist, slide the edge of the blade toward the bottom coin in the stack. The bottom coin is ejected from stack. The stack of coins drops without tipping over.  The process can be repeated, making the stack of coins progressively shorter. With practice the spatula can be slid back and forth very rapidly as coins are knocked out from under the stack. You may want to place "coin catchers" at the ends of the table.

Presentation:
This activity creates much excitement in the classroom, especially as coins or washers begin to fly around the room. You should make provisions for safety if you use this as a student activity.  Allow students to discover the role friction plays in this activity. Direct them to experiment with the minimum "flick rate" required to overcome the effect of friction. If they slide the blade too slowly, friction will cause the upper coins to tumble over.  Students can use different combinations of coins, washers, game tokens, spatulas, rulers, to create their own version of this activity.

Content:
This a classic inertia demonstration. It demonstrates the first of Isaac Newton's Three Laws of Motion, published in 1687: A body remains at rest or, if already in motion, remains in uniform motion with constant speed in a straight line, unless it is acted on by an unbalanced external force. This principle of inertia was Newton's explanation of the "laziness" of an object, its apparent unwillingness to change unless acted upon. The term inertia is from the Latin term meaning idleness.  The spatula provides the external force which overcomes the bottom coin's tendency to stay at rest. It is friction and air resistance which cause the coin in motion to come to rest.

Student Critique: This experiment was really cool and fun and easy. It takes a few tries, so stick with it and be creative! (21%)

22. Bernoulli Cans

Description:
Two empty soft drink cans are placed on several drinking straws. Air pressure forces the cans to roll toward each other.

Standards: Employ simple equipment and tools to gather data and extend the senses (Standard A.1.3). Use data to construct reasonable explanations (Standard A.1.4). Scientists develop explanations using observations and what they already know about the world (Standard A.2.4). The position and motion of objects can be changed by pushing or pulling. The size of the change is related to the strength of the push or pull (Standard B.2.3).

Content topics: air pressure, inertia and Bernoulli principle
You will need: 24 drinking straws, 2 empty soft drink cans, flat, smooth table top
Instructions:
This is a simple activity. However, practice this activity before presenting it to your students. For the best results, the activity should be presented on a smooth and level table top.
Place 23 straws on the table parallel to each other, about 1 cm apart. Place the cans upright on the rank of straws. The cans will be able to roll freely, back and forth.
Position the cans approximately 5 cm. apart. Using the remaining straw, blow between the cans. The cans roll towards each other, colliding with a clang.
Presentation:
Although this activity is fairly simple, if affords several opportunities to model prediction and analytical thinking. First demonstrate how easy it is for the cans to roll back and forth on the straws. Explain to your students how you are going to blow between the cans and ask them to predict what is going to happen.
Many students will suggest that the cans will roll apart due to the additional air you are forcing between the cans. Ask students, "Other than the straws, what is touching the cans?" (Answer: air). Is blowing between the cans going to increase the air pressure momentarily by adding more local air, or decrease the pressure momentarily by "knocking" some of the local air out of the way?
If students suggest that the cans will roll towards each other, ask them to explain their prediction. What are their prior experiences that would allow them to make such a prediction? (Answer: wind blowing over a sheet of paper and "lifting" it; something getting "pulled" into a current).  Allow students to blow between the cans, causing the cans to come together. Direct them to make a top-view drawing of the two cans and use arrows to indicate the forces of air pressure. They should indicate that the air pressure between the cans decreases and the air on the outer sides of the cans forces them together.

Content:
In 1738, a Swiss mathematician Daniel Bernoulli studied the relationship between the pressure and velocity of a fluid. The Bernoulli Principle states that the pressure of a liquid decreases as its velocity increases.  That principle applies to the two cans. As the velocity of the air between the two cans increases (being blown away), the pressure the air it applies to the inner sides of the cans decreases. That allows the air on the opposing sides of the cans to push the cans towards to the area of lower pressure. Make certain that your students understand that the air pressure on the outer sides did not increase, rather it was the decrease in pressure between the cans that allowed the cans to roll towards each other. The cans were not "sucked" together. They were pushed together.

Student Critique: This experiment really surprised me, I did not think the cans would move at all.  Then it really got me thinking about molecules and things moving that I cannot see - definitely one for the classroom. (100%)

23. Potato Float

Description: A slice of potato mysteriously floats in the exact center of a glass of water.
Standards: Use appropriate tools and techniques to gather, analyze, and interpret data (Standard A.1.3). Use data to construct a reasonable explanation (Standard A.1.4). Objects have many observable properties (Standard B.1.1).
You will need: three tall beakers or glass tumblers, water, sugar, spoon, knife, potato
Instructions:
Cut several 2.5 cm wedges from the potato. Try to cut the pieces to the same size. This is a density activity. Students might be misled if they see that the pieces are not all the same size.
Make a strong sugar solution by dissolving sugar in water. Dissolve sugar until a piece of potato will float in the solution. If the solution appears cloudy, allow it to stand for a few minutes until it clears.
Fill one glass with the clear sugar solution. Fill a second glass with pure water. Fill the third glass half full of sugar solution. Very carefully and very slowly pour pure water on top of the sugar solution in the second glass. Pour the water down the side of the glass or use a spoon or glass rod to direct the stream against the side of the glass. If you are careful and avoid too much mixing, the less dense water will "float" on the sugar water. The sugar water should be clear enough to prevent any indication that the second glass is filled with anything but water.
Make certain that all three glasses are filled to the same level. Carefully place a wedge of potato in each glass. The potato floats at the top of the liquid in the first glass. The potato sinks to the bottom of the second glass, and it sinks to the middle of the third glass.

Presentation:
Before your presentation, fill the three glasses with the proper solutions. Do not allow students to see how you made the sugar solution, or how you created the layered solution in the third glass.
Place a piece of potato in the first glass. The piece of potato floats. Ask students which is more dense; the potato or the liquid? (the liquid)
Place a piece of potato in the second glass. The piece of potato sinks to the bottom. Ask students which is more dense, the potato or the liquid? (the potato)
Inform students how you made the solutions in the first two glasses. (The first is sugar-water, the second is pure water.)
Place a piece of potato into the third glass. The potato sinks, stopping at the middle of the glass. Inform them that you used only sugar and water to make the solution in the third glass, but do not tell them how you did it. Ask students to share their thoughts concerning the third glass. How do they think you did it? Challenge them to use sugar and water to create the effect themselves.

Content:
The density of water is 1 gram/milliliter. The density of saturated sugar-water (common household sugar) is ~1.83 grams/milliliter. Sugar-water is almost twice as dense as water. Most varieties of potatoes have a density of ~1.6 g/mL.

Student Critique: This experiment took a bit to organize, but still very cheap and in the end made a worthwhile, important point.  You may with to try other ratio's of solutions and even other variables added to the water to make this presentation better. (21%)

24. Straws - several quick, easy demonstrations about our friend, the straw.
Straw is defined as a stalk or stem of dried, threshed grain, like wheat, rye, oats and barley.  The first drinking straws were cut from stalks of grain.  How does a straw work? 
Materials: Straw, cup, water.

Straw I:
Procedure: Suck a little water into the straw.  The hold your finger across the top of the straw and take the straw out of the water.  Place the straw over an empty class.  Then remove your finger from the top of the straw.  

Lesson: Your finger across the top lessens the pressure of the air from above the straw.  The greater the pressure of air under the straw holds the water inside it.  When you suck through the straw, you are not actually pulling liquid up.  What you are really doing is removing some of the air inside the straw.  This makes the pressure inside the straw lower than the pressure outside.  The greater pressure of the outside air then pushes the water in the glass up through the straw and into your mouth.

Student Critique: This experiment was very quick and easy and the students could actually do it themselves over and over.  I really liked this one. (21%)

25. Buttons and Spaghetti
Description: Demonstrate chemical change and matter, even gases occupy space.

Resources: Several colored buttons no larger than 2 cm, clear drinking glass, clear carbonated soda;  500 mL of potable water, 3 mL baking soda and some vinegar
Procedure:  1. Dancing Buttons.   Fill glass with soda to 2 cm from top, drop buttons into glass, if it floats, tap to bottom.  Small bubbles begin to form around button, suddenly button rises to top, knock glass, bubbles will fall off and button will sink. 
2. Dancing spaghetti. Break uncooked spaghetti into 2 cm pieces and put them into a glass of water and baking soda.  The will sink.  Then stir in 3 tablespoons vinegar.  The vinegar (acetic acid) will combine with the baking soda (calcium carbonate) and form carbon dioxide bubbles which adheres to the spaghetti and raises it to the top, it pops and sinks to bottom again.  Add food coloring for effect.

Student Critique:  This was very easy to do and very cheap.  I realized I could use many other objects for this demo and then possibly have the students bring in things and try it. (88%)

26. Straw Activities
Resources: Straw, water.
Procedure:   Hold the straw upright, with one end on the table, grasp the paper covering at the top of the straw and push the paper firmly down to the bottom of the straw.  Remove straw, measure and examine magic worm - OBSERVE.   Use the straw to place a drop of water on the worm and examine expanded worm.   
For the next demonstration, start at one end of the straw and twist the end a couple of times. Then twist the other end a couple of times. Now that both ends are twisted shut, hold one end in each hand. Keep twisting the ends and the untwisted middle part will keep getting shorter and shorter. Once the middle part is down to about two inches long, have a friend flick the center of the straw with their fingernail. If they flick it hard enough, you will hear a fairly loud pop.
How can a twisted straw make such a sound? It is just like popping a balloon. As you twist the ends of the straw, you are squeezing the air inside into a smaller and smaller space. The compressed air is pushing outwards on the sides of the straw. When your friend's fingernail hits the straw, it causes the straw to split, letting the air rush out. The expanding air pushes the air around it, creating a wave. When this wave hits your ear, it makes your eardrum vibrate and you hear the sound.

Student Critique:  Great demo to do anytime and anywhere.  It is very cheap, the materials are everywhere, even in a school lunchroom. (50%)

27. Air Pressure

Procedure: Take a straw, cut it in half, place one piece vertically in a cup of water, place the other piece horizontally next to the top of the piece that is in the water, and blow through the horizontal piece. The water in the vertical straw should rise and spray out since the air pressure above the straw is less than the air pressure above the water in the cup.  The air pressure above the water in the cup literally pushes the water in the straw up and out.   This is how pump spray bottles, like some perfume bottles, work.

Student Critique:  Definitely one I would do in class and a great way to begin any discussion of gases or phase changes. (58%)

28. Air Pressure II

Materials: Film canister with a snap-on lid. Look for a clear film canister, if possible.
- Soda, Alka-Seltzer® tablet, safety glasses, paper towel for clean-up, watch or timer, notebook, adult helper

Alka-Seltzer Rocket
1. Put on your safety glasses.
2. Divide the Alka-Seltzer tablet into four equal pieces.
3. Fill the film canister 1/2 of the way full with water.
4. Get ready to time the reaction of Alka-Seltzer and water. Place one of the pieces of Alka-Seltzer tablet in the film canister. What happens?
5. Time the reaction and write the time down. How long does the chemical reaction last? Why does it stop? Empty the liquid in the film canister into the waste bucket.
6. Repeat the experiment, but this time place the lid on the container. Remember to time the reaction. Write down your observations.
7. You should have two pieces of Alka-Seltzer tablet left. Repeat the experiment using one of the pieces of Alka-Seltzer, but this time you decide on the amount of water to put in the film canister. Do you think that it will make any difference?
8. Use the last piece of Alka-Seltzer to make up your own experiment. What do you want to find out? How are you going to do it? What are you going to measure?
9. Go ahead and experiment!

How it works:
The first part of this experiment is just a variation of the classic Alka- Seltzer film canister rocket. The same principle is at work here. In both cases, carbon dioxide gas builds up so much pressure the lid is forcibly launched. With an Alka-Seltzer tablet, the CO2 is produced as a result of a chemical reaction. With the soda, the CO2 is produced as a result of vigorous shaking. This provides a good contrast between a physical and chemical change. You may need to experiment with several different film canisters before you are successful at building a rocket that launches with a blast. If the lid fits too tightly or too loosely, it will not work. To avoid a sticky mess, seltzer water can be used, which is simply carbonated, sugarless water.

Student Critique:  You can also do this with vinegar instead of water and chalk instead of Alka-Seltzer. (96%)

29. Coke Density
Purpose: To provide additional resources for attention, engagement and stimulation of relevant science.

Resources: One can of soda, and one can of diet soda and a large container of water.

Procedure:  Take one of the cans in your left hand and one of the cans in your right. They probably feel about the same; same size, same weight. Now set both of the cans in your large container of water. What happens? One of them sinks and one of them floats.

Do you know why this happens? Do you know why ANYTHING floats in water rather than sinks. The reason has to do with relative densities of materials. The density of water is 1g/cm^3. If the density of an object is less than one, then the object floats in water. If the density of an object is more than one, the object will sink in water.
Now we know that the density of one of the cans is greater than 1 g/cm^3 and the density of the other is less than 1 g/cm^3. What could account for the difference? Let's assume that there is the same amount of liquid and air inside each of the cans. Let's also assume that there is the same amount of aluminum in each of the cans. NOW what can you think of that could make the different in densities.
The answer is that there is a difference in density between the two cans because of the difference in density between sugar and the sugar substitute used in diet soft drinks.

Student Critique:  Great, practical demo - we all drink this stuff! (77%)

30. Sound

Procedure: Take 4 rubber bands with the same lengths but with different widths and wrap them around a textbook.  Place one marker under the rubber bands at the top of the book and another at the bottom of the book.  Pluck the rubber bands.  The thicker rubber bands should produce a lower pitch than the thinner ones.  This is how a guitar works. 

Discuss sound, wavelength, pitch, etc.

Student Critique:  Nice, normal demo since we have all played with rubber bands at some point - cheap, too. (22%)

 31.Cloud in a Bottle

Ever wondered how clouds form? This demonstration allows us to witness cloud formation before our very eyes!

Materials:
- One liter, clear plastic bottle with cap - Water - Match

Method:
- Place a small amount of water in the bottle (just a splash is sufficient). - Light a match and drop it in the bottle and quickly cap the bottle. - Squeeze the bottle 6 or 7 times (more squeezing may be necessary) and watch the cloud form!

How it works:
In order for water droplets to form and make a cloud, they need particulate matter (small particles) around which to form. This is the purpose of the smoke from the smoldering match. The cloud forms when the air cools as it expands, thereby reducing the temperature in the bottle below the dew point. The moisture then condenses as a cloud. Clouds on Earth form when warm air rises and its pressure is reduced. The air expands and cools, and clouds form as the temperature drops below the dew point.

In this demonstration you were able to make the air in the bottle compress and expand simply by squeezing the sides of the bottle and increasing and decreasing the air pressure.

Student Critique: Definitely a 'wow' demo, students can really get into this one. (56%)

32. Stab the Spud

Materials: Stiff straw, unwrapped - Big, raw potato - Paper towels

Method:1 Stab the straw through the potato without bending or breaking the straw. Most of your guests will think it can’t be done but you, of course, know better.

2. As you hold the potato, keep your fingers on the front and thumb on the back and not on the top and bottom. Grab the straw with your writing hand and (this is the secret) cap the top end with your thumb. Hold on firmly to both the straw and the potato and with a quick, sharp stab, drive the straw into and partway out of the narrow end of the spud and not the fatter middle part. 

3. Your audience will be impressed and want to try it. Tell them to hold the spud the way you did so they don’t stab a finger or thumb with the straw. They may not know the secret so don’t give it away just yet. Oh, you may need more stiff straws for them, too.

How it works:
The secret is inside the straw: it's air! Placing your thumb over the end of the straw traps the air inside. When you trap the air inside the straw, the air molecules compress and give the straw strength; which in turn keeps the sides from bending as you jam the straw through the potato. The trapped, compressed air makes the straw strong enough to cut through the skin, pass through the potato, and out the other side. Without your thumb covering the hole, the air is simply pushed out of the straw and it crumples and breaks as it hits the hard potato surface.

Make sure to keep your fingers out of the way. After you stab the straw, take a look at the end that passed through the potato. There’s a plug-o’-spud inside the straw. If you should have a finger or thumb or hand in the way of the straw as it collides with the potato, then there will be a plug-o’-you in the straw, too.

Student Critique: I didn't think this would work, but amazingly it did! (88%)

33. Polymer Action - This activity is best practiced over the sink. When you’ve mastered the art of Spear-It, then you can present your newly acquired skill at the dinner table.

Materials: 5 pencils with round edges - 1 Zipper-lock plastic bag - Paper towels - Pencil sharpener - Water

Method: 1. Start by sharpening the pencils. 2. Fill the bag 1/2 full with water and then seal the bag closed. Pose this question to your dinner guests, “What would happen if I tried to push one of these pencils through the bag of water?” Will the water leak out and make a giant mess?” 

3. Here comes the scary part. Hold the pencil in one hand and the top of the bag in the other hand. Believe it or not, you can push the pencil right through one side of the bag and half way out the other side without spilling a drop. The bag magically seals itself around the pencil. Sounds impossible? Continue to rekindle your “spear-it” for science by jabbing the remaining pencils through the bag.

Make sure the tips of the pencils are sharpened to a point. Be careful not to push the pencils all the way through the bag or your “spear-it” experiment will turn into a big “clean- up-the-water” activity.

How it works:
The plastic bag is made out of long chains of molecules called polymers. This gives the bag its stretchy properties. The sharpened pencil slips between the molecule strands without tearing the entire bag. Believe it or not, the long chains of molecules seal back around the pencil to prevent leaks.

Student Critique:  Super!  (100%)

34. Create Your Own

 Develop or find your own demonstration. 

Student Critique: