1. Everyday Math
Grade 1
Lesson 9.4

2. 9.4 Adding and Subtracting 2-Digit Numbers
Objective: To provide practice adding and subtracting 2-digit numbers.
Math Journal , 183
Math Masters 262, 263
slate
animal cards from Unit 5
Number-Grid Poster
base-10 blocks
number cards 0-9 (2 of each)
1 penny per partnership
bath scale & objects to weigh (ELL option)
graphic licensed from

3. Mental Math and Reflexes:
Is 17 closer to 10 or 20?
Is 24 closer to 20 or 30?
What multiple of 10 is closest to 33?
What multiple of 30 is closest to 68?
What multiple of 70 is closest to 86?
Is 120 closer to 100 or 200?
Is 175 closer to 100 or 200?
Math Message:
Take out your animal cards. Look at the side that shows the animal's length in inches. Which animal is the shortest? Which is the longest?
Home Link 9.3 Follow-Up
How did you use the number-grid patterns to complete the puzzles?

4. Creating and Solving Silly Animal Stories
Suppose the rabbit and the raccoon lie nose to nose.
What will be their total height?
parts-and-total diagram
This is how to use the Number-Grid
to solve the problem of: ?

5. Silly Animal Stories
If the Koala stood on top of the penguin's head, how tall would they be together?
If the fox sat on top of the beaver, how much would they weight together?
How much taller is the boy than the girl?
Check your answers with the number grid.

6. Silly Animal Stories
Make up number stories about comparing or finding total lengths or weights of two animals. Student Page, Math Journal 2, Page 182

7. Name-Collection Boxes, Lesson 9.4
Math Masters, page 262

8. Student Math Journal 2, page 183
Math Boxes

9. 14 + 16 = ________ l.... + l...... = lll 24 + 57 = _________
Practice for Home Link 9.4
Solving problems in two ways.
= ________
l l = lll
= _________
ll lllll = ________ l .

10. Home Link 9.4
Solving Problems in Two ways

11. See differentiation options, Teacher Guide, Pages 176-172
Practicing 2-Digit Addition and Subtraction with base-10 blocks
Comparing the sums of 2-digit by 2-digit addition problems with
animal cards
Comparing the Weights of Objects

12. We did good work and the lesson is finished!