One array, two useful parts
Use facts you know to work out a new product by splitting and recombining an array.
Explore this lesson →10 practice questions · Optional read aloud · Thinking pad
Let’s understand the idea.
- Split each row into two parts. Both parts keep the same number of rows.
- Multiply to count the left part and the right part. Add these partial products to find all the objects.
- Try another split of the same array. The partial products change, but their sum stays the same.
Something to notice
Ask the learner to explain why both parts keep the same number of rows, choose a useful split for a new product, and connect the picture to an equation. Six questions require both partial products and the total; three use given facts with a numerical response; one probes the common error of multiplying only one part. This lesson addresses the distributive strategy within 3.OA.B.5; commutativity, associativity and division applications require additional instruction. Formal property names and practice completion do not establish understanding or mastery.
Try it. Change it. Explain it.
Open the lesson to use its pictures and controls. In How it works, connect the picture to the idea. In Play & discover, change the quantities and notice what stays the same. In Your turn, answer questions and use the explanation to check your reasoning.
You can ask for help, draw on the thinking pad, or listen to the question and answer options. Progress distinguishes independent work from work completed with help.
Let’s try it →Curriculum connection
Grade 3 · 3.OA · US Common Core
This lesson is mapped to these standards. A completed activity is practice evidence, not a claim of mastery. Content is checked against the linked official standards and its mathematical models are tested.