Really Easy and Quick Science Demonstrations

Teaching science is enhanced when students have high-interest teacher demonstrations that make important science facts easier to understand.

1. Point: heat is the movement of molecules

 Procedure: put 400 ml cool water (50 F) in a beaker and an equal amount of 100 F in another beaker. While students watch, put one or two drops of food coloring into each. The food coloring in the warmer beaker will diffuse through the beaker with warm water within minutes due to the faster motion of the molecules.

2. Point: to see how colors mix to make difference colors

Procedure: cut a strip of paper towel about one inch by 12 inches. Using a blue water soluble maker (E.g.: Vis-à-Vis) and make a dark mark about one inch from one end of the strip. Suspend the paper towel in a beaker of water so that it just touches the water below the blue mark. As the water is soaked upward by capillary action, it will separate the different colors in the blue dye and move them slowly up the strip. Allow 5 to 10 minutes for the separation. Blue works best, but green and read are interesting as well.

3. Point: Effect of evaporation on cooling

Procedure: wrap the bulb of a lab thermometer in a single ply of toilet tissue. Wrap around only one or two times and wet the tissue. Note the temperature of the air in the room before beginning. Gently wave the thermometer around or back and forth, stopping every 15 seconds or so to note the temperature which should drop as water evaporates and cools the bulb. This works well when the air is dry (humidity < 50), but will usually produce results inside on any day. After two or three minutes the temperature will level off. Compare on a rainy day and the temperature drop will be less. Students can do this as a simple experiment.

4. Point: How density affects buoyancy

Procedure: pour a clear carbonated drink (like Sprite) carefully into a clear, tall drinking glass. Add about 10 fresh raisins. Initially, the raisins will tend to sink because they are denser than the drink, but as bubbles of carbon dioxide attach to the raisins, they reduce the density and cause the raisins to float to the top. The bubbles will burst at the surface and the raisins will sink again. This will continue for several minutes until the carbonation (CO2) has been lost.

5. Point: demonstrate magnetic field

Procedure: Use ceramic neodymium magnets to show how magnetism can penetrate matter. A small pair of can be obtained at stores like Walmart, some tool outlets, Radio Shack, etc. They are strong enough to separate iron from cereal (like Total) after cereal has been mashed to crumbs and added to water in a Ziploc bag. Hold the magnet against the outside surface of the mixture and tiny particles of iron will be attracted to the magnet. Neodymium magnets of about one cm diameter have a magnetic field strong enough to allow one to be placed on the back of the hand and hold on to another one on the palm of the hand. Be careful! They can snap together with such force that they can pinch! 

6. Point: The "sound" of contracting air (best in cold weather)

Procedure: Have students collect two-liter soft drink bottles -- with caps-- until each student can have one bottle for the demonstration. On a cold day -- 45 F or colder outside -- have student screw the caps on the empty bottles and walk outside. As the cold air outside cools the air in the bottles, the air in them will contract causing outside air pressure to push the sides of the plastic bottles inward creating "crackling" sounds. The contraction of the bottles will be visible as dents. When they return to the classroom, the effect will be reversed and the bottles will expand. Be sure students screw the casps on tightly.

7. Point: Observing with the ears

Procedure: Students often think that observation is done with the eyes only. Place a common object (paper clip, rock, coin, key, etc). Conceal the object in a small box or can. Ask students to try to identify the object by the sound it makes when the container is shaken or gently rotated. Call attention to the types of clues they are using to make their conclusions.