## Cavern

# Cavern

Send the climber across the cavern by clicking on the opposite wall. Collect the jewels on the cave walls and watch out for bats. When you have collected all the jewels, they will be displayed in a ten frame. There will be an equation based on the ten frame. Choose the number which makes the equation true, to proceed to the next level. There are 5 levels. Each successive level has more bats to avoid.

### Common Core

Grade 1 » Operations & Algebraic Thinking

CCSS.MATH.CONTENT.1.OA.D.8

*Work with addition and subtraction equations.:* Determine the unknown whole number in an addition or subtraction equation relating three whole numbers. For example, determine the unknown number that makes the equation true in each of the equations 8 + ? = 11, 5 = _ – 3, 6 + 6 = _.