After reading @ChrisHunter36’s post: http://reflectionsinthewhy.wordpress.com/2013/06/09/more-decimals-and-ten-frames/ I could not believe I had never thought to use 10 frames when working with decimals.
Today we began our unit on decimals and I decided to use the 10 frame (now called a “one frame” in my room) as a quick image to get a feel for how my reason about decimals as a part of a whole and the types of equations they could write to represent the way they viewed the frame.
I started with this frame:
I had to explain how we used this as a visual in K-2 to build combinations of ten and later use more than one frame for students to think about addition and subtraction strategies. One student then asked, “Um, how are we going to use them in 5th grade?” Perfect intro. We came to the conclusion that in the younger grades each box is equal to one making the whole frame equal to ten, hence the name.
Me, “Well, what if the whole frame was 1? What would each box be?
Student, “1 tenth.”
Me, “Great and how can we write that?”
Student, “1 over 10 or point 1.”
Me, “So what decimal does the frame on the board represent?”
Student, “Five tenths.” Everyone gave a quick shake of their hand in agreement. (The signal in our number talks)
Now that we had the basic understanding, I did a quick image flash of this frame:
1 – 0.1 = 0.9
0.5 + 0.4 = 0.9
9 x 0.1 = 0.9
Then of course the comedian that just loves to make me write more than necessary… 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 = 0.9 He would laugh to think he now got me to type that out as well 🙂
We were moving fast through this so I thought I would throw out two frames to see how they reasoned about going over the whole. I know from past experience that some students will line .9 + .3 up vertically and add straight down to get an answer of .12, it is the most common mistake that I think using the one frames will be helpful in minimizing by providing students the concrete visual of a whole.
I flashed this quick image next and asked students to write what number is represented by the two frames and equations that represent how they “saw the dots.”
I saw 1.2 and 0.12 in journals as I walked around, but then a student shared out that he thought it was 12/20. I LOVE when a student does this…makes it so much more interesting. I wrote all three answers on the board. I asked them who believes their answer is correct, they all raised their hands (confident bunch), so I told them to choose one of the the other two answers and explain what the misunderstanding is that led to that answer. I got some great work that we shared out and agreed finally on 1.2.
Here is what they said…
So, thanks so much to Chris. I can see many One Frames in my future number talks!