This week I heard lots of “ooohs!” and “aaahs!” and “what’s happening?!” in the 7th grade class.  This excitement is exactly why I love teaching science!  The 7th graders were trying to make sense of chemical reactions by mixing rock salt, baking soda, and water.  When the three substances were placed in a tightly closed plastic bag students noticed that the bag got hot, bubbles and fizzing were produced, the bag inflated and a creamy paste-like substance formed.  What’s happening here?  Some students think that the substance created a mixture.  Others think new substances were formed.  And, still others think that this has something to do with a chemical reaction.  Which is it?  We’ll find out more next week!