Gallon Man revisited

It’s become a rite of passage in many 2nd – 4th grade classrooms. Crafting Gallon Man. For the past five years, we did it too, and I was always thoroughly disappointed when my students didn’t remember their capacity conversions as well as I hoped they would. Even singing a sweet little ditty didn’t help. I like this song a lot better.

It’s daunting to talk about what doesn’t work in our classrooms when we have good intentions, but Sherlock urged me to write about how I changed things this year.

So this year when we started our measurement unit, I shared realia of the four main capacity units in the United States. We talked about how the units are related (see conversions in brown) then drew two common versions of Gallon Man.

Instead of sending them off to cut and glue their own gallon people, I told them that during independent work time, they’d need to create their own visual representation of capacity.

I explained that their visual representation of capacity must be meaningful to them so they would remember the conversions. Some of theirs wound up looking pretty much like mine, which was just fine.

I said that they could be as creative as they wanted as long as they were accurate mathematically. I also asked them to write a brief explanation of how their visual representation could be used. For example, in the representation above, I went back and asked the student what she meant when she said “the number of pints in a cup.” She said, “Oh, I got it backwards! Because the way I wrote it, it’d mean half a pint in a cup.” Which is correct, but not what she intended to say.

And in this representation, the overall number of cups in a gallon was accurate (16), but they were distributed incorrectly (three cups in each quart on his feet, and four cups in the pint on his tail). We talked about how he could change his representation to be mathematically correct while still keeping his artistic integrity (taking off the tail hairs and adding an extra claw to each feet).

This one was mathematically correct:

They worked during Math Daily 5, and most finished by the end of the day. The rest made sure they picked Work on Writing or Math by Myself during Math Daily 5 later in the week so they’d finish everything.

The next day, as we went over our representations, we also discussed why we needed to create a memory device for capacity, even though we don’t really need to come up with anything to remember, say, the number of days in a week or the number of inches in a foot. Here’s what they came up with:

I’ll assess their application of this learning later next week using our district unit tests as well as a scavenger hunt using a plant book so it connects to our science unit. I’ll try to remember to post that too.

As always, I’d appreciate any feedback you have on this lesson.