[Putting out one ten-frame] If I have one ten-frame, what’s the biggest number I could show? (10)
[Adding a second ten-frame] Okay, if I have two ten-frames, what’s the biggest number I could show? (20)
At this point, I thought they would make the connection, so I asked them to look at their ten-frames, talk with their partner, and decide the biggest number they could show with four ten-frames. They still did not come up with 40. This was fascinating to me! Once again I repeated my questions about one and two ten-frames. I added a third empty ten-frame and asked what the largest number I could show would be (30). I then asked them the original question again (“What is the largest number you could show with your four ten-frames?”). They finally decided 40, but this just shows how much support our Tier III kiddos need!
Back to the planned lesson…I wrote the number 26 on my whiteboard and chose a student to read the number. I have learned not to assume students can read 2-digit numbers when they see them in isolation. Then I asked the students to work with their partner to build the number. While all the students successfully built the number, it was fascinating to see that most students were counting by ones as they put their counters on the ten-frames. After they had built the number, I asked them if they had to count by ones and reminded them that if the ten-frame was full, it was ten. We continued practicing this throughout the lesson (“If it’s 26, how many filled ten-frames will you have? Which digit shows you how many filled ten-frames you will have?”).
On my whiteboard, where I had written 26, I wrote the equation 26 = 20 + 6. I asked the students to talk to their partners about what this equation meant. They were able to tell me that the 20 was the two filled ten-frames and the 6 was the counters on the ten-frame that wasn’t full. It is not obvious to children that a filled ten-frame can be called a ten, and that when we have two filled ten-frames it is two tens but represents 20 counters. HUGE concept and hurdle in understanding.