This lesson asks students to use their understanding of the structure of a number (MP7) and apply some repeated reasoning (MP8) to help them solve problems. Students have had multiple opportunities to build concrete models of numbers. In this lesson, they take their understanding of the "tens place" to help them solve multiple problems. Students with a deep understanding of place value will understand that the tens place will always help them know how many groups of 10 are within a larger quantity, connecting back to the idea of repeated reasoning.
Yesterday we saw a pattern in how we write these numbers. We started to see that one of the numbers, the tens place, told us how many tens we need. And one number, the ones place, told us how many ones we needed.
Today we will see if we can make things into groups of 10s. 10 is a number we often group into. When Ms. Cole counts, she uses tens to help her count quickly. When we sell stickers at the sticker shop, each page has 10. Grouping things into 10s helps us do math in the real world.
Objective : Your thinking job today is: What does the number tell me about how I can break it into groups of 10?
Present Problem: The sticker shop has 30 stickers. They put 10 stickers on the strips. How many strips of 10 will they have?
After reading the problem, lead students in a series of questions that help them "make sense of the problem" before they persevere through solving it (CCSS Mathematical Practice 1).
Follow up with: “Wait! We are making tens! Each strip will have 10 so we are making groups of 10. This is a break into 10s problem. We need to make 10s.
Now I want you to figure it out on your own. Let’s read it one more time. We have to pay super close attention to figure out what is happening.
See attached video for more on the "Break It Into 10s" hand motion and chant!
I'll give students 7-10 minutes to work on the problem.
After student work time, I'll bring students back together for a strategy share.
I'll choose 1-2 strategies for students to share. See attached picture for our class chart!
Restate student thinking: When we are solving problems that ask us to break numbers into 10s, the number is helping us figure that out. We have to be on the eye out for Break into 10s problems! They want to know how many tens are in the number.
Goals: Students build the number using cubes or single stickers, then put it into groups of 10. After making the groups of 10, I'll have students circle the number that tells them how many tens to make the connection more explicit.
Group B: Right on Track
Goals: I'll push these students to predict how many tens before building out of sticker strips. I'll ask, "What in the number can help us predict how many tens?"
Group C: Extension
Goals: Students at this level are consistently using structure of number and understand that one digit tells them how many tens. I'll push these students by giving them numbers off the decade. This will push them to see how many tens and how many extra ones.
For independent practice sheets and sticker strips and singles, see attached documents.