Use addition and subtraction within 100 to solve one- and two-step word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using drawings and equations with a symbol for the unknown number to represent the problem.
Cognitive Complexity Level: 1-Recall
[divider] [/divider] Students are able to…
- Solve one and two-step addition and subtraction word problems with unknowns in all positions.
- Model word problems using various concrete and pictorial representations, i.e., base ten blocks, part-part-whole chart, open number lines, linking cubes, etc.
- Write equations to represent one and two-step word problems.
- Explain how an equation connects to their concrete/pictorial models.
- Make sense of one and two-step problems by labeling the numbers (ex. 32 marbles).
- Decide if their answers are reasonable and justify their thinking.
[divider] [/divider] Students are able to…because teachers:
- Select appropriate one and two-step addition and subtraction problems for student to solve.
- Connect and model writing equations based on students’ models and explanations.
- Help students focus on the missing information needed to solve a problem, instead of key words (when deciding which operation to use).
- Provide numerous opportunities for students to share, explain, and compare their strategies with others’.
- Use formative assessment to determine when students are ready for an increase in the range of numbers and writing equations independently.
[divider] [/divider] Questions to ask students:
- Which operation did you choose to solve the problem? Why?:
- Sample answer that indicates understanding: “I chose addition to solve because there were some blue markers in the bin and some red markers in the bin. When I put them together, or add, then I can find the total markers in the bin.”
- What do the numbers in your equation represent in the problem?:
- Sample answer that indicates understanding: Ex. 53-31=? “The 53 represents the number of stickers on the front cover. The 31 represents the 31 less stickers that are on the back cover. The question mark, what I have to find out, is the number of stickers on the back cover.”
- Does your answer make sense? How do you know?:
- Sample answer that indicates understanding: “I know that my answer makes sense because I labeled the numbers in my equation and it matches my base ten blocks. I also used a number line to solve it another way and I got the same answer.”
- What does the equal sign in your equation mean?
- Sample answer that indicates understanding: “The equal sign means ‘is the same as’.”
[divider] [/divider] Additional Resources:
Additional in depth content knowledge
Blog Post: Numberless Word Problems
LearnZillion Lesson: Understand a Word Problem
LearnZillion: Solving Two-Step Word Problems Using a Model
[divider] [/divider] Sample Formative Assessment Tasks:
[divider] [/divider] Resources/Tasks to Support Your Child at Home:
- Mathplayground Game: Have your child apply multiple strategies and write equations to solve word problems in game format
- Encourage your child to directly model one and two-step word problems, recording their work using quick pictures, bar models and/or open number lines.
- Kahn Academy Video: Adding and Subtracting on Number Line (Word Problems)
- Task: Riley has 18 snails in a bucket. He finds more. Now he has 43 snails. How many more snails did Riley find? What equation could you use to solve this problem?
- LearnZillion Lesson: Understand a Word Problem
- Task: There were 38 people on a bus. 14 people get off at the first bus stop. Then 22 new people get on the bus at the second stop. How many people are on the bus now?