## 1st Grade Games - Use place value understanding and properties of operations to add and subtract.

Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.

Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.

Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90 (positive or zero differences), using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used.

Screenshot Name / Description Flag? Rating
Math Pac Man
Treasurement
Help the pirates get their gold by choosing the right answers
Ghost Blasters
Race with another player to add two numbers and blast ghosts
Number Twins
Select the number twins that add up to 10.
Math Man 2
Fly through the air and hit the correct number for the equation.
Math Mountain
Climb the mountain by getting math problems correct.
Timed Test