- Worksheets
- Games
- Lesson Plans
- Workbooks
- Exercises
- Science Projects
- Skills Progression
- More
You are here:
Lesson Plan
Mystery Addends: Representing Word Problems
Make a math mystery! In this lesson, help your students understand the relationship between addition and subtraction and how a missing addend word problem is represented with a number sentence.
Download lesson planGrade
Subject
View aligned standards
Learning Objectives
Students will be able to use mental math to solve missing addend questions using both addition and subtraction strategies. Students will be able to represent a given missing addend word problem using a number sentence. Students will be able to identify the initial, change, and result of a word problem.
The adjustment to the whole group lesson is a modification to differentiate for children who are English learners.
Introduction
(10 minutes)
- Tell the students that today they will be reviewing fact families, or related numbers, and they will use that knowledge to help them represent missing addend word problems.
- Remind your students that an addend is a number in a problem that is being added.
- Show the example of a fact family triangle to the students, and have them explain the relationship between the 3 numbers.
- Tell the students that they will make their own fact family triangles and play a game with them.
- Pass out the triangles, and have the students each write out a fact family.
- Then, have them walk around the room to find a partner to answer the question.
- Direct each student to cover up one of the 3 numbers and show it to his partner.
- Next, have your students find new partners and do it again.
- After they have asked several peers, have them sit down.
- Instruct your students to keep the triangles in their desks to play later.
Beginning
- Ask students to identify the larger number (18) and the smaller numbers (7 and 11). Model counting on from 11 to 18 as you think aloud, "11 + 7 = 18. If I know this fact, I also know that 7 + 11 = 18."
- Use manipulatives or a number line to show students that 18 - 7 = 11 and 18 - 11 = 7.
- Show students a few more examples of fact families before excusing them to make their own fact family triangles.
Intermediate
- Remind students that fact families include two addition and two subtraction facts. The number at the top is the sum, or total, of the two parts in the bottom corners.
- Write ________ + ________ = ________ and ________ - ________ = ________ on the board. Model solving for the third number in a fact family using both addition and subtraction.