Heat Inquiry

For this week's inquiry experiment I used 4 identical coffee mugs, one cup of hot water, and covered each mug with a different material: a plastic Tupperware lid, plastic wrap, aluminum foil, and a potholder.  I thought that the potholder would prevent the greatest heat loss because of what I know about insulators and how we use potholders.  After thirty minutes, I measured the temperature of each mug.  To my surprise, the mug covered with the potholder was the coolest of all four, and the mug with aluminum foil ended up being the hottest. 

After doing a little research, I learned more about latent heat of vaporization and how evaporation causes cooling.  As the water evaporated from each mug, the different materials covering allowed for more or less evaporation.  The potholder absorbed a lot of the heat that was escaping, while the foil held it in.  The condensation on the foil may have even fallen back in the cup thus reducing the cooling effect.

I thought about this experiment this morning on my way to church.  I often put instant oatmeal in a coffee mug and take it with me in the car to eat on the go.  This morning my oatmeal was too hot to eat right away so I let it sit in the cupholder to cool a bit.  I began wondering how the temperature of the oatmeal would different from the water in my experiment if left to sit for 30 minutes.  Also, would oil hold heat longer than water? 

I enjoyed gaining a deeper level of understanding of heat and hope to convey this to my students as well.

Guided Inquiry on Momentum

This week I chose to explore whether a heavier pendulum or lighter pendulum would come to rest more quickly.  My initial hypothesis was that the heavier one would rest faster due to the pull of gravity.  After testing washers with two different masses, I found that actually the lighter washer came to rest in a quicker time (in about 4 minutes versus about 7 minutes on the heavier washer).  The variables were a little difficult to control such as the length of the string and being able to tell when the pendulum had come to a complete rest. 

I am having a hard time making parallels to my own classroom because we do not cover Newton's laws in third grade.  I could somehow integrate magnetism into this lesson and have students make connections to different size and strengths of magnets and how they may slow a pendulum.  This would meet my standards as well as prepare students for momentum in fourth grade.

Ultimately, I learned that a greater mass produces greater momentum.  This momentum takes longer to slow.  If I conducted a similar guided inquiry lesson with my students using magnets, I would want them to discover that a stronger attraction will cause the pendulum to slow more quickly.  This could be applied to real-world tools and machines that use magnets.