I love our science teacher

Every elementary school has a science teacher. The good ones can inspire a love of science that lasts a lifetime. I think we've got one of those at our school. Every week he (I won't mention his name because I haven't asked his permission) sends out a short email to all the parents describing what the kids are doing in science class that week, so the parents can talk about it at home with the kids and maybe get them to show how the experiment worked. Here's this week's installment, short and sweet:

Dear Parents,

We have been studying chemistry since the winter break. This week we made cold packs and hot packs.
We made cold packs with an endothermic chemical reaction (absorbs heat) mixing baking soda & lemon juice in a sealed sandwich bag. We made hot packs with an exothermic chemical reaction (releases heat) mixing calcium chloride (rock salt used to melt ice on roads) and lemon juice. We then made a list of indicators of chemical reactions based upon what we have done in class: bubbling, inflating (a sealed bag),explosions
(firing rockets), change of temperature, and change of color of acid/base indicator. It can be tricky, though. Except for a change of the acid/base indicator, none of the indicators guarantee a chemical reaction. For example, there is no chemical reaction in a just opened bubbling bottle of pop. By definition, a chemical reaction occurs if some new substance is created.

[The Science Teacher]

So easy. So magical. Thanks, Mr. Science Teacher!