This sight has lots of instructions for simple games and also free printables
Kids love using dominoes during math! Great for missing addends...
Missing numbers to 100
Classroom Freebies Too: 120 Chart Math Freebie
before and after number
Missing Addend Freebie Worksheet
Here's a hundred board covered by snakes. Students must determine and write the missing numbers.
Ten More/Ten Less Freebie
Robots - Find the Missing Addend Freebie