Use Unifix cubes, five frames, ten frames, and number bonds, to explore ways to make numbers 1-10. For example, 4 can be shown as 1 red cube and 3 green cubes. For at least one of the small numbers, arrange in an array, such that students can see 0 + 4 = 1 + 3 = 2 + 2 = 3 + 1 = 4 + 0. I think this is good for students to see enumeration, that is, all the ways something can be done. This is a good brush for later when they study combinatorics in high-school.

Watch the first part of this video:

Composing Numbers & Decomposing Numbers! by Scratch Garden

Making small numbers in different ways by Khan Academy

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K.OA.A.3: Decompose numbers less than or equal to 10 into pairs in more than one way, e.g., by using objects or drawings, and record each decomposition by a drawing or equation (e.g., 5 = 2 + 3 and 5 = 4 + 1).