Week 11MondayDecide: Add or Subtract?
1Warm-up: ±10 Mental Math

2-min Fluency Warm-up — Mental math: add or subtract 10.

42 + 10 =

75 − 10 =

36 + 10 =

88 − 10 =

2Number Talk: Choose Your Operation

Number Talk — Read each situation. Do you ADD or SUBTRACT? Explain WHY.

You had 24 marbles. Your friend gave you 18 more.

Add or subtract? ______

Why?

There were 67 birds on the wire. 32 flew away.

Add or subtract? ______

Why?

The bookshelf held 35 books. You added 28 more.

Add or subtract? ______

Why?

The cookie jar had 83 cookies. Someone ate 41.

Add or subtract? ______

Why?

3Mixed Practice

Read each problem carefully. Decide if you add or subtract, then solve.

28 + 35 =

72 − 28 =

46 + 37 =

85 − 39 =

4Find the Missing Number

Find the missing number.

8 + = 15

− 7 = 20

+ 36 = 84

91 − = 57

5Challenge: Create Your Own

Challenge — Write 2 addition problems and 2 subtraction problems.

Make them interesting! Use numbers you find cool.

Addition 1:

Addition 2:

Subtraction 1:

Subtraction 2: