This lesson is built around 1.OA.D8 and 1.OA.1, both of which ask students to be able to solve for missing numbers in any part of the story problem. Where this gets trickiest is being able to represent what happened in the story in numbers. The standard specifically asks students to use a symbol to represent the unknown, so in this lesson, students use a storyboard "puzzle" to help them figure out where the symbol (or as we call it, the mystery box) will go for the unknown part of the problem.
I'll open the lesson by reading The Tale of Peter Rabbit. Using favorite read alouds helps get students engaged in the problems for the day and allows me to incorporate literacy throughout my day. You can project Peter Rabbit on the promethean board for free from Wegivebooks.com. It requires a free login and then you unlock dozens of books to read online!
Today we are going to solve some problems about bunnies eating carrots in our garden. As we do this, we are going to think about which part of the equation is missing.
Your thinking job is: Which part of the story problem is missing? What equation can I build to match?
Peter Rabbit has a bunch of carrots in his pocket. He eats 4 of them. Now he has 11 carrots left. How many carrots did he have at first?
I have a frame here for my number sentence. I have to fill in each part with the number or a mystery box.
I'll point to each part of the box and model retelling the story. I want students to see that the numbers/symbols I write in each of those boxes will correspond to a specific part of the story. This is aligned to CCSS MP2, Reason abstractly and quantitatively. Students can contextualize the numbers that they write in an equation back into the context of the story. They understand what each number and symbol represents.
For each question, I will have students read the specific sentence within the story problem that corresponds with that part of the equation. This is aligned to the CCSS shift towards always being able to cite evidence-this helps kids practice what they are already doing in our reading block!
See the attached image for the Anchor Chart!
Partner talk: What is the answer to this story problem? Show your partner how you solved.
You can watch the attached Partner Discussion and see how a few students discussed this problem. You'll see that one student solves the problem incorrectly, both of his partners explain what they did but he isn't convinced. Don't be afraid of these situations in your own classroom! This shows that the culture is such that students can stand firm in their answers. Instead, I waited to have a child model this problem with cubes and then touched base with the student later. He needed to see the concrete model to figure out exactly where his mistake was.
Present problem: Student Share Peter Rabbit Problem.docx is attached!
There are 13 bunnies in my garden. When it starts raining, some of them run away! Now there are 6 bunnies. How many bunnies ran away?
Guiding Questions: Students practice processing these questions with a partner so they internalize it for their own independent story problems later. CCSS MP1 (Make sense of problems) asks students to read a problem, interpret it and plan a strategy for it.
Student Work Time: Students get 5-6 minutes to work on this problem.
See the attached picture of the Class Chart we made!
Students solve story problems similar to the student share problems on their own. I differentiate the problems based on number size.
Peter Rabbit Math Problems.docx are attached!
Students partner up with someone in the same group (A, B or C) and assess each other's work. The focus question is: Do you think your partner's equation is correct? Why or why not?