### Common Core State Standard

### 2.OA.B.2

Fluently add and subtract within 20 using mental strategies. By end of Grade 2, know from memory all sums of two one-digit numbers.

*CCSS: 2.OA.B.2*

In the left corner we have you, the world champion adder. In the right corner we have every world champion adder wanna-be in town. Time to duke it out. May the best adder win!

*CCSS: 1.OA.C.5, 2.OA.B.2*

Click the numbered orbs to create a total of 10 before any of the orbs reach the top. Use your bombs and clocks wisely to get a high score..

*CCSS: 1.OA.C.5, 2.OA.B.2*

Play Tetris with numbers. Clear numbers from the board by dropping numbers so they add up to the target number. Lots of levels to choose from.

*CCSS: 2.OA.B.2*

Use your addition skills to get the space cars safely through the intersection. Stay on top of things so they don't crash!

*CCSS: 2.OA.B.2*

Click on numbers as fast as you can to come up with the given difference. Get a high score and you can send a challenge to your friend!

*CCSS: 2.OA.B.2, 3.OA.C.7*

Help Mr. Moomoo stop the alien invasion by answering addition, subtraction and multiplication questions. Get to the baddies' home planet to put an end to it.