Many years ago I came out to my car and set my coffee cup on top of the car while I opened the door.  I was shocked when I moved the cup and saw a bullet.  It was most shocking because I had no idea when it happened or where.  I was coming out of a coffee shop. The concept that what goes up must come down is very real.

This isn’t that same concept but is just as real of a law as gravity.  This is the law of conservation of mass – matter cannot be created nor destroyed it only changes forms.  Balancing equations is where we want kids to visualize this concept.  There are lots of great ways to make this more hands on.

• Create a balance
• Use different color beads and a table
• At the very least make a table.

I think the best way to get kids to take ownership and dig in deep is to make a mess.  You can do this experiment with a little baking soda and vinegar, but there are things that you can add to make it have more wow factor.

How do you get the wow in the law of conservation of mass?

You simply have students play with proportions of baking soda and vinegar until the reaction doesn’t overflow the container (I think a 50mL graduated cylinder works nicely).  Make sure that the kids all start with a reaction that overflows the container – you can play with the proportions for the container you use.  Then have them experiment (making sure to record how much of their reactants).

This can be done with lots of other reactants, but I love using chemicals that are safe in the classroom and the environment.

Don’t want to worry about creating your own worksheets?  Grab this conservation of mass lab activity.

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