In teaching number sense it is important to provide instruction on friendly numbers. Doubles are one type of friendly numbers that students love to rely on, when solving addition problems that feature multiple addends.
This document is intended to train students to identify doubles, when presented with a string of addends. My students enjoy searching for the doubles, identifying the doubles, and then correctly coloring the doubles.
I tell my students that this activity 'trains their eyes' to find friendly numbers before attempting to solve!