February 24, 2010
by: Ron Perkins
Who knew that a single coin could be used for so many classroom science activities! You can demonstrate concepts such as surface tension, buoyancy, and even eddy currents with Japanese yen coins!
Surface Tension: Even though aluminum has a density of 2.7 gm/cm3, and the density of water is 1 g/cm3, aluminum yen coins can float on the surface of the water!
Surface tension is a physical property of water. It is caused by cohesion, which is the attraction of like molecules. Water molecules are made up of two hydrogen atoms and one oxygen atom. The “stickiness” of water is caused by hydrogen bonding. This hydrogen bonding pulls the water molecules towards one another and forms a sort of “skin” on the surface of the water.
Japanese Yen Coins Experiment 1:
Using a bent paper clip or a plastic fork, gently lower the flat side of the coin onto the surface of a pan or cup of water and remove the clip or fork. The coin should rest on the surface of the water. Read the rest of this entry »
February 12, 2010
by: Tami O’Connor
The W-Tube is a device that was invented and developed by Ron Perkins, Chemistry and Physics high school teacher for 33 years and founder of Educational Innovations. This amazing teaching tool was designed to have students in every grade level, kindergarten through high school, discover and gain a deeper understanding of concepts relating to density and air pressure.
In order to solve each puzzle, students need to have a basic understanding of density and air pressure. Depending upon the grade level of your students, you may want to conduct a few experiments or demonstrations prior to having them attempt the W-Tube challenges on their own. The following two activities do not utilize the W-Tube, however they will provide some younger students with the background knowledge necessary to successfully complete the W-Tube challenges.
This first activity is a valuable demonstration that shows that air takes up space. Start by balling up a paper towel or tissue and affixing it to the bottom of a plastic cup using two-sided tape. Invert the cup with the tissue inside and then push the plastic cup into a clear container of water so the cup is completely submerged. Your students should be able to see that, although the air is somewhat compressed within the cup, the paper at the “top” of the cup remains dry. Read the rest of this entry »