Separate Result Unknown

Connie had 13 marbles. She gave 5 marbles to Juan. How many marbles does she have left?

Modeling:

Strategy: Separate From:
13 - 5 = ?


Strategy: Separate To:
13 - ? = 5


Strategy: Join to:
5 + ? = 13

Counting:

Most counts are kept with their fingers, counters, or tally marks. Here are ways to record their thinking.
Strategy: Count Down:
13 - 5 = ?

Strategy: Count Down To:
13 - ? = 5

Strategy: Count Up To:
5 + ? = 13

Derived Facts:

Strategy: Number Facts

I know 5 = 3 + 2 (decompose 5)

So: 13 - 3 --> 10 - 2 --> 8

Notice: It isn't 13 - 3 = 10 - 2 = 8