This is one of my favourite lessons that I did on my second practicum in a grade 1/2 class. It was a part of a unit on measurement but I’ve found that it’s also a great stand alone lesson in most primary classes.
I always start the lesson in a circle with a pathway made out of masking tape in the middle of the path on the floor. We then have a discussion about wanting to see “how long” the path is (you could also do this as a comparison to a straight line path too). Then I use something to “measure” the path and ask students to put their hands up if they think there is something I need to do differently. The last time I did this I used clothes pins and the mistakes I made were things like starting the measuring not at the end of the tape, putting the pins vertical and horizontal, or leaving a gap between clothespins – The kids caught all the mistakes!
The next step is using something that won’t work very well to measure the path – usually used crayons of a variety of different sizes. I have them count how many crayons it takes and use lots of little pieces to get them laughing as we count really high. Then we talk about why the crayons didn’t work very well to measure the path and how using a new box of crayons might work better.
After I have students think (thinking time – no hands up) about what objects they could use to measure the tape path and then we go around in a circle and share our ideas. We always talk about the objects that may or may not work (a good discussion came up last time about whether or not lego pieces were a good idea to use because of their different sizes). Then I choose a few of the objects suggested, split the kids into small groups and make a bunch of tape paths on the floor, tables, desks, etc. that they get to measure in their groups. We rotate stations and they end up using all the different materials while measuring a bunch of different paths.
Some groups may finish quicker than others so I often give extra challenges like having them measure using the unit in a different way (sideways, standing up, etc.) and I also carry a role of tape around with me so I can quickly add a new path to keep students engaged if need be.
I really love the discussion that comes out of this lesson and I hope you get a chance to give it a try!