You know in movies/tv shows usually at a moment of desperation they say something like, “Well, we’ve been testing something but it’s not quite ready yet…” but then they release the weapon or whatever and it saves the day? (Think the ‘crashed’ alien spaceship in Independence Day.)

Yeah, this lesson was sort of like that.

California has been in a drought for a number of years, and this took place in early to mid 2014. I was working on an investigative lesson for students involving rainwater, perhaps wolfram alpha etc. In the spirit of a three act task, I wanted to have them estimate something and then actually solve it.

Well, one day it started raining during a block period (so I had twice as much time with first period) and I just went for it.

I had a graduated cylinders in my class due to using density to teach about ratios. So we set them outside and for an hour they collected rainwater. I asked the students what questions they could ask about the rain and then we voted what to solve for. Questions of course started out as, “How much rain is coming down?” but other students correctly reasoned how could we figure that out. Eventually they realized if we knew how much rain was coming down inches-wise, and we found the area of Fresno (roughly) we could figure out the ‘volume’ of water coming down and then even the weight. Of course some exceptionally thoughtful kids realized that rainfall wouldn’t be 100% consistent but we decided that was ok to not include for now.

Wikipedia was used to find the area of Fresno; kids also printed out maps of Fresno and used their skills in creating/finding the area of irregular polygons to find the square miles of Fresno. We talked about acres vs square miles and other measurements of area. Some kids found an approximate answer (I don’t remember) but not everyone did and the period was over.

Here’s the cool part. Towards the end of the class I told them that sure, I had something else planned for that day, but wasn’t it fun to do something spontaneous? Most kids were ambivalent (we’re talking about 7th graders here) but one kid wrote me a note after class saying something like, “That was really fun, thanks for making math interesting and a class I look forward to every day!”.

Lesson Idea: How Heavy is the Rain on Your Town?

Necessary Supplies: Graduated Cylinders, Access to Internet

Standards: 6.G.1, 7.G.1, 7.G.6, probably others

Math Practices: 1,2,4,5,6