This is a double set of 10-frame cards. Print on colored cardstock (2 pages per set) to make it easy to tell at a glance which set each card belongs to.
Students gain many skills while playing with 10-frame cards including subitizing, adding to nine, adding to 20 by visualizing making a 10 and what is left, and subtracting in the same way. 10-frames provide a way to visually learn math facts before (or after) introducing terms such as "adding" or "subtracting".
Games are readily available online but a couple that work well are:
Around the World
Memory/ matching games