After a two week break, we’re back to class today.  One of the perks of homeschooling is that you can go camping when everyone else goes back to school and have the campground to yourself.

Today we did the Chapter 2, Lesson 1: Heat, Temperature and Conductivity lab from the American Chemical Society’s Middle School Chemistry.  My grocery store didn’t have styrofoam cups so I bought some insulating cups made from plants (eco friendly – yeah) but they  didn’t do a very good job insulating.  For the experiment we had 4 or 5 metal washers tied together by a string soaking in room temperature water and a separate cup with hot water.  The students recorded the temperature of the water with the washers and the temperature of the hot water.  Then they placed the washers in the cup with the hot water and watched the temperature.  We also had a control cup containing just hot water because if you leave a cup of hot water sitting on the counter, it will cool off all by itself.  The kids correctly predicted that the washers should bring down the temperature of the hot water.  The problem is that the control went down by the same amount.  So we decided to double up on cups for the second experiment to increase the insulation value and we put  the lids on the cup.

The second experiment is just the reverse of the first one.  This time the washers were left in very hot water and then placed in room temperature.  The water’s temperature went up briefly before it started to cool.   I expected the results to be bit more dramatic then they were.  I think using ice water and very hot water might work better.

Before we did the experiment I held a saucepan and metal spoon in my hand and asked the students what would happen if I left the spoon in the pan while cooking.  They all shouted that it would get hot.  I then held up a wooden spoon and asked the same thing.  They all instinctly knew that it wouldn’t get as hot as the spoon.  So I talked about how heat is conducted differently by different materials and metals tend to be good conductors of electricity and heat.

The ACS curriculum actually has some links to some nice little videos showing the temperature of molecules and how they transfer energy to each other.

http://www.middleschoolchemistry.com/multimedia/chapter2/lesson1#heating_washers