Recently we did a unit on Rocks with our science curriculum. This sounded pretty boring to me, but the girls really enjoyed it. We got a kit containing 16 different types of rocks and conducted tests to determine which was which. We also learned about the three main classes of rocks and made models of them.
I am so conflicted about teaching science. I hate the mess and clutter created by the experiments. But the second I even hint that we will do a science experiment, the girls jump up and down with excitement. They frequently re-create the experiments for Robby when he gets home and I have even caught them doing modified versions of the experiments with their dolls weeks later. So, I do try to incorporate as many of the experiments as I can into the day.
Igneous rocks are made from molten rock which has cooled & hardened. So we made a mini-volcano with a toilet paper tube covered in wax paper. Then we melted chocolate chips in the microwave and poured it into the "crater." As the crater overflowed, the pretend lava flowed down the mountainside. In a few hours, the liquid chocolate cooled and (surprise!) hardened. Sabrina especially loved this project because she got to eat the igneous rocks we made.
The third main type of rock are metamorphic, which are igneous and sedimentary rocks which are changed by heat and pressure. I forgot to photograph this, but we pretended that a corn chip was a rock and put "pressure" on them with our hands, crushing them and, therefore, changing their shape. They re-create this experiment all the time - every time we have corn chips now.
We did not do an experiment to demonstrate how heat changes the shape of rocks - I couldn't find one that seemed simple enough.
The girls had a lot of fun with these experiments!