Lesson 3 Add and Subtract Within 20
Let’s add and subtract within 20.
Warm-up Number Talk: Use Known Sums
Find the value of each expression mentally.
Activity 1 Many Ways to Add and Subtract
Circle 1 addition expression and 1 subtraction expression.
Find the value of the expressions in as many different ways as you can.
Show your thinking using drawings, number, or words.
Activity 2 Heads Up
Write an equation for each round you play.