I read the book One is a Snail, Ten is a Crab to two Kindergarten classes this week. If you have not read the book, Marilyn Burns does a great post about it here. After reading aloud, making predictions and doing a notice/wonder, I placed 10 tiles in the middle of our circle in an arrangement like this:
I asked the students who could be standing on the beach and they quickly guessed a dog, two people and two snails. I asked if they could give me an equation for the feet they see and they said 4 + 2 + 2 + 1 + 1 = 10. I asked if anyone had a different equation and they switched the order of the numbers, but agreed there was still 10. I did a few more arrangements before sending them back to their groups to investigate with the tiles. The directions were for one student to put out the arrangement, the groupmates guess who was standing on the beach, and write an equation for what they see. Their equations were all so different but the ways they were composing and decomposing the tiles to make new arrangements was really interesting!
We brought them back to the carpet and asked what they noticed about all of their equations. They said they all ended in 10 and equaled 10, so I asked if that meant we could write the equations so they were equal to each other? I asked two groups to share one of their equations and I put them equal to one another on the board. I asked if that was true? How could be we prove it? Their first answer was like, duh, they both equaled 10 so yes. I asked if they could combine or break apart any of the numbers like they did with their tiles to prove it. One student talked about combing the 1’s circled in the picture below.
They had to leave for lunch so I left them with an equation to talk about when they got back!
This lesson was such an amazing way of allowing students the space to think about equality and the meaning of the equal sign. It took one student talking about the ways he combined the numbers to open up the conversation and possibilities for future equations. I would love to see what the students could do if I wrote one equation on the board and asked students to write all of the different ways they could fill in the other side of the equal sign.