A Great Day: Powdered vs. Solid

A few weeks ago my morning class made my day.  We’ve been studying physical and chemical changes in matter in sixth grade science.  A lot of our labs have come from the Mixtures and Solutions FOSS kit.  Say what you will about labs in a box, but I’m a fan of FOSS kits.  The students like them too and their experiences with the labs are very useful references when we get around to reading or taking tests about science concepts.  The only down side about some of these labs has been my need to start and stop students during the experiments as they progress through the procedures.  It can be hard to get the kids’ attention back once they’ve started, understandably.

On this particular day, I did not use a lab from the FOSS kit.  We were addressing the following Louisiana grade-level expectations:

Determine the effect of particle size of the same reactants on the rate of chemical reactions during a lab activity (e.g., powdered vs. solid forms).

What I loved about this day was how much I didn’t have to do.  I framed the above GLE as our question to investigate.  I showed them the reactants we’d be using, which were generic brand Alka-Seltzer tablets and water.  Then I asked the class for some suggestions about how they might investigate the question of how particle size relates to reaction time.  I told them that today I wanted them to come up with their own procedures in their groups.  They didn’t have to write them down, but they needed to be able to explain to me how they were controlling variables and conducting a fair test that would answer the question.  I told them they would have enough tablets to test them out more than once in case they felt like they weren’t able to answer the question with their first set of procedures.  I passed out tablets, beakers, and timers and pointed to where the water and the buckets were (gotta love a sink-less science classroom) and let them get to work.

I couldn’t believe how engaged and self-sufficient the entire class was.  Every group was on task.  There was no race to the water pitchers, no arguing over who got to hold the beakers.  I didn’t have to assign jobs or signal when to start and stop.  Instead, I walked around and listened to students come up with plans for crushing some tablets while leaving others whole.  I watched them cleaning out their beakers between trials to make sure the residue from the previous tablets didn’t affect the next tablet’s reaction time.  They created data tables, drew diagrams and felt confident in their discovery that the powdered tablet reacted faster than the solid tablet.  Did this discovery rock their world?  Probably not, but their ability to stay focused, work togehter pleasantly and apply what they’d learned about controlling variables from previous labs to this one definitely rocked mine.