Represent 10 using a number bond and 10-frame to help solve a Mystery Math Mistake. Use Notice and Wonder with an unbalanced see-saw to tell whether two expressions are equal. Then, practice with telling whether two expressions are equal (balanced).

Math Mights was adapted from IM K-5 Math™ ©2021 by Illustrative Mathematics®, released under the Creative Commons Attribution 4.0 International License (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/.

Additions and adaptations are ©2021 by Strategic Intervention Solutions, LLC.

Apply properties of operations as strategies to add and subtract. Examples: If 8 + 3 = 11 is known, then 3 + 8 = 11 is also known. (Commutative property of addition.) To add 2 + 6 + 4, the second two numbers can be added to make a ten, so 2 + 6 + 4 = 2 + 10 = 12. (Associative property of addition.) (Students need not use formal terms for these properties.)

Relate counting to addition and subtraction (e.g., by counting on 2 to add 2).

Understand the meaning of the equal sign, and determine if equations involving addition and subtraction are true or false. For example, which of the following equations are true and which are false? 6 = 6, 7 = 8 – 1, 5 + 2 = 2 + 5, 4 + 1 = 5 + 2.