The Coordinating Units sequence helps children understand the base-10 place value system. It develops reasoning for coordinating groups of ten with individual units — foundational for addition and subtraction with numbers greater than twenty. The sequence has two parts: Part I focuses on single quantities, and Part II addresses sums and differences. Both parts move from physical materials (Unifix cubes) to reasoning through visual imagery, using an extended “candy shop” context (packing candies, circling candies, and candy flash activities).
We recommend watching the videos in order.
Video Group 1: Sequence Overview and Coordinating Units Part I
Becoming Efficient With Reasoning About Coordinating Units With A Single Quantity
Segment 1.1 — Tens and Ones
Segment 1.2 — Tens and Ones
Segment 1.3
- CU Notes for Video Group 1 (PDF)
- Ms Wright's Candy Shop (PDF)
- Circling Candies 1–4 (PDF)
- Candy Packing 1–3 (PDF)
Video Group 2: Coordinating Units Part II
Becoming Efficient With Reasoning About Sums and Differences By Coordinating Units