Warm up with a Mystery Math Mistake as you add two 2-digit numbers using a decomposition strategy. Think through creating your own centimeter ruler. Estimate and measure with a centimeter ruler.

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.