Act it out!
Lesson 7 of 10
Objective: SWBAT choose a strategy to solve a problem. SWBAT solve a problem using cubes or counting on.
Setting Up the Learning
This lesson has students make sense of problems and determine whether or not each story is a put together or a take away problem. We specifically focus on the counting on strategy in this lesson. This is aligned to 1.OA.C5, relate counting to addition and subtraction. We discuss a student's work where they counted on and relate this counting on strategy to a count all strategy, asking-how are these the same? How are these different? This lesson is also aligned to MP1-Make sense of and persevere in solving problems. Students are having to think about how they are going to approach solving the problem, and then represent the story using cubes, fingers, counting, etc.
Yesterday we talked about whether or not a problem was a put together problem or a take away problem. Today we are going to look at some of the ways our friends solved that problem.
We always have to think about how we solve problems-we have to think about what strategies we can use to help us solve problems quickly and strategies we can use anywhere.
Your thinking job today is: How can I use cubes and counting to help me solve this problem?
I’ll choose 2 strategies from the day before (See previous lesson here). One strategy should be cubes based, one should be counting on based.
“I have 2 strategies from yesterday that I want us to discuss.” (I’ll draw both on chart paper and narrate as I do so)
- This person put out 5 cubes, then they got out 1 more cube. They counted 1, 2, 3, 4, 5, 6.
- Partner talk: How did this person solve the problem?
- Partner talk: What did this person do to solve the problem?
- Why did they say 5, 6? Where did the 6 come from? Why did they stop at 6?
- How are these 2 strategies different?
- Which strategy was a little faster? Why was it a little faster? (Emphasize that mathematicans always use efficient strategies)
- Which strategy could you use at the grocery store? You could definitely count on in your brain! You don’t need cubes for that!
Now we have another problem to look at. When we solve this problem, we need to think about the strategies we just looked at.
Let’s read this problem two times: I had 4 books on my desk. My teacher put 2 more books on my desk. How many books are on my desk?
Partner talk: Retell the problem to your partner.
Student Work Time and Share
During work time, I’ll be looking for someone who tries counting on. I'll give students 8-9 minutes to work on this problem.
Bring students back together, I’ll say, “I saw a friend choose ___’s counting on strategy! Let’s see how they used counting on to solve this problem. (You might choose someone who used fingers to count on here)
- Why didn’t they count the first group?
- How did they count on to solve it?
- Why did they stop at 6?
- Let’s try this strategy together. I’ll have students explain and try this strategy with a partner.
You'll find the differentiated problem sets here: Counting On.docx. Here is a quick explanation of how I differentiated:
Group A: Intervention
These students probably are not ready for counting on quite yet. I’ll have them focus on representing the problems with cubes. When I talk with students in these groups, I’ll have them show me how to count the cubes. Then I’ll say, “I am going to use counting on to solve” and quickly recount them to expose kids to the strategy.
Group B: Right on track
I want to push these students to try counting on. If kids are using cubes or fingers, I’ll say, “How many are in this group? Do you need to count them again?”
Group C: Extension
See this video for pushing kids towards Representing How They are Counting On.wmv.
See this Student Work Example for one way a student explained her counting on strategy in pictures, numbers and words.