Yesterday, I brainstormed my plan for the 2nd grade lesson I taught today. I started by giving each pair of students a set of things to count and I asked them to explain how they counted and why they chose to count that way. I was excited to see such a variety of counting strategies such as 2’s, 5’s 10’s and then combinations of all of these. As I walked around, this is what I saw…
As a whole group, we shared strategies for counting and the students discussed how they combined the numbers. I then had them switch their container with another group. They were all mixed up so they didn’t know how many were in the new container. With this container of objects, I asked them to see if they could split the contents into two equal groups.
I don’t know if my thinking is even on track here, but since Tara had mentioned students were struggling determining whether a number could be divided equally into two parts without physically passing out each one, I thought having students think about the ways in which they count in comparison to splitting a number in half, could be helpful here. For example if a student is trying to divide 42 into two equal teams, he or she could think that two 20’s would be 40 and 2 left over to give to each 20 to make 21. Or even four 10’s and 2 ones, so each team gets two 10’s and then a one from the two leftover. Like I said, I could be completely off-base but it proved to be an interesting trial!
As I walked around I saw some really cool halving going on!
This group did a visual split symmetrically and then each counted their “half” and then they passed them back and forth until they had the same amount. Like a guess and check. It seems something like finding half of 46….”I know it is 20-something, so you take 20, I have 26, here take 1 of mine, now it is 21 and 25, so take 2 more of mine and now we each have 23.”
I saw the completely symmetrical works. not counting at all, they just lined them up by twos and said their plan was to “push the two rows apart.” It seems like counting by 2’s to get to 46 and then seeing how many times you had to do that.
This group did what I was hoping to connect to the counting they did earlier. They grouped them in 10’s and then split them in half. They ended up having an odd number and wanted to put that in decimals so bad. There was a lot of .5 talk. So interesting!
Then I saw a student who counted them by one’s and then divided the number he got in half. (The top part is is counting group, the bottom is the halving of a different number.)
We ended with a journal entry on any similarities and/or differences we saw between the counting and the dividing into two groups. Sadly, I had to leave to go down and teach Kindergarten, so I have to pop back up to check out their journals tomorrow. I think that could be a great place for Tara to start tomorrow and then do a number talk about splitting a number into two equal groups.
I still have to think on this lesson more. I learned a lot about how the students count in 2nd grade, which after being in a Kindergarten class was really fantastic and I loved the way they saw symmetry in sets. That was beautiful. However, I think there are are some other great connections to be made here but I am not sure it was helpful connections for everyone. Most students seemed to have some great strategies for halving so I am wondering what they took away from this? I have to pop back up tomorrow and see what the journals say to see if I can get a better read on the class.