# This is a lesson on inverse addition and subtraction sentences

Subject:

Math

K

Title – Creating your own Number Sentences!
By – Taylor Washington
Primary Subject – Math

Texas Essential Knowledge and Skills Standards:

111.2.b Mathematics, Kindergarten.

(K.4) Number, operation, and quantitative reasoning. The student models addition and subtraction. The student is expected to model and create addition and subtraction problems in real situations with concrete objects.

Learning Objectives:

• Students must be able to name and describe the function of all the parts of an addition/subtraction problem. (Example: sum = answer to an addition problem)
• Students must be able to rearrange three numbers into all possible addition/subtraction number sentence combinations. (4 combinations)
• Students must be able to fill in the missing answer to an addition/subtraction problem with single digits. (Ex. 7-2=?)

Materials:

• Worksheet/three numbers written in the corner (one number being the sum of the other two) and four simple math problems.

Procedure:

1. Have all the students seated at their desks where they can clearly see the overhead screen.
2. Discuss with the students the different parts of a number sentence. Difference, sum, addend, etc.
3. Pick three random one-digit numbers, or have the students help. One number being the sum of the other two.
4. Have the students raise their hand to call out the different number sentences you could make using those three numbers.
5. Write down the different number sentences one on top of the other on the overhead.
 3 + 5 = 8 8 – 3 = 5 8 – 5 = 3 5 + 3 = 8
6. Explain to the students why this works / make sure everyone understands.
7. Pass out worksheet with three numbers in the corner (just like the numbers you picked for the overhead). The worksheet also has four math problems with a difficulty to match the number sentences we are working with. (Ex. 4+4=?)
8. Have the students make the four possible number sentences out of their numbers and complete the problems. Go around the room checking individual work.
9. Gather their attention back to you as a class.
10. Have your closing thoughts making sure that all the students understand the lesson.
11. Have the students turn in their worksheets to their cubbies.

Closing thoughts:

• Now you need to check their understanding.
• Ask some students to explain the inverse relationship between addition and subtraction in their own words. Make sure to call on the students you know understand, because they will explain it well.
• Call on students you know had trouble to make sure they now fully understand.
• Verbal questions to ask at end of lesson: 4+6=? What is an equals sign used for? Etc.
• If they need additional practice send them to a website such as: www.321know.com/add34ax1.htm