Count forward by ones between two given numbers. For example, from 13 to 21. Count forward by tens between two given multiples of ten. For example, from 20 to 90.

Missing numbers by Khan Academy

Conclude by leading this investigation:

Hex (strategy game)

by MathPickle

K.CC.A.2: Count forward beginning from a given number within the known sequence (instead of having to begin at 1).