Lesson objective: Understand that the amount remains the same even when objects are counted in different ways.

Students bring prior knowledge of counting from K.CC.B.4 and K.CC.B.5. This prior knowledge is extended to counting objects in irregular arrangements (up to 10 objects) as students count accurately. A conceptual challenge students may encounter is thinking that the number of objects changes when we recount or rearrange them.

The concept is developed through work with organizing objects, which helps students learn to be accurate in their counting.

This work helps students deepen their understanding of equivalence because regardless of the way each set of objects is arranged, the amount remains the same.

Students engage in Mathematical Practice 6 (attend to precision) as they develop strategies for counting accurately and efficiently.

**Key vocabulary:**

- array
- circle
- count
- line

**Special materials needed:**

- blocks, cubes, counters, or other objects to count (ten per student in a bag or container).