1. Adding and Subtracting Meters and Centimeters 3B: 6.1c

2. Adding m & cm with no renaming  2 m 60 cm + 25 cm = _____ m _____ cm  How do you get the answer?  Since there are no meters in front of 25 cm, just add the centimeters. 852

3. Adding m & cm with renaming  2 m 60 cm + 75 cm = _____ m _____ cm  You can still add the centimeters since there are no meters in front of the 75 cm.  60 cm + 75 cm = 135 cm  Can you leave the 135 cm as it is?  Convert it into m and cm.  1 m 35 cm 2 m 60 cm2 m 135 cm = 3 m 35 cm + 75 cm 335

4. Another way  You could also make 100 with either 60 cm or 75 cm. 35 cm 25 cm 2 m 60 cm 75 cm 1 m + 2 m 35 cm + = 3 m 35 cm

5. Another way  Now let’s make 100 with the 60. How much do we need from the 75?  How much is left? 35 cm 40 cm 2 m 60 cm 75 cm 1 m + 2 m + = 3 m 35 cm 35 cm

6. One more strategy…  You can add the numbers up vertically.  First, convert into cm.  Add.  Convert back to m and cm. 2m 60 cm + 75 cm 260 cm + 75 cm 335 cm 3m 35 cm

7. Adding both meters and centimeters  2 m 65 cm + 3 m 20 cm = _____ m _____cm  Use mental calculation to add the meters.  Then add the centimeters. 2 m 65 cm + 3 m 20 cm 5 m 65 cm + 20 cm 5 m 85 cm

8. Adding both meters and centimeters  Try this one…  2 m 65 cm + 3 m 40 cm = _____ m _____cm  Add the meters.  Then add the centimeters and rename. 2 m 65 cm + 3 m 40 cm 5 m 65 cm + 40 cm 5 m 105 cm 6 m 5 cm

9. Use vertical adding, if you prefer  First, convert into cm.  Add.  Convert back to m and cm. 2 m 65 cm +3 m 40 cm 265 cm + 340 cm 605 cm 6 m 5 cm

10. Subtracting both meters and centimeters  5 m 30 cm – 25 cm = _____m _____ cm  To find the answer, subtract 25 cm from 30 cm. There are no meters to take away so the 5 m stays the same. 5

11. Subtracting both meters and centimeters  5 m 30 cm – 75 cm = _____m _____ cm  Take 100 cm from the 5 meters. What’s left?  Subtract the 75 from the 100.  Add the remaining cm together. 4 55 5 m 30 cm 4 m 30 cm100 cm 75 cm =– 75 cm– = 4 m 30 cm + 25 cm = 4 m 55 cm

12. Other strategies  Is there another way to solve the problem 5 m 30 cm – 75 cm?  You can rename 5 m 30 cm.  Then subtract. 5 m 30 cm – 75 cm = 4 m 130 cm – 75 cm = 4 m 55 cm

13. Use vertical subtracting, if you prefer  First, convert into cm.  Subtract.  Convert back to m and cm. 5 m 30 cm – 75 cm 530 cm – 75 cm 455 cm 4 m 55 cm

14. Subtracting when you don’t have to rename  5 m 30 cm – 2 m 25 cm = ____ m _____ cm  How should we solve this?  Subtract meters first.  Then subtract centimeters. 5 m 30 cm3 m 30 cm3 m 5 cm – 2 m– 25 cm

15.  How do we find the difference between 5 m 30 cm and 2 m 75 cm?  Let’s look at three subtraction strategies… 5 m 30 cm – 2 m 75 cm = 3 m 30 cm – 75 cm = 2 m 130 cm – 75 cm = 5 m 30 cm 2 m 30 cm100 cm 2 m 75 cm =– 75 cm– = 2 m 30 cm + 25 cm = 2 m 55 cm 2 m 55 cm 3 m 30 cm75 cm =– 5 m 30 cm – 2 m 75 cm 530 cm – 275 cm 255 cm 2 m 55 cm RENAME CONVERT MAKE 100

16. Now you try.  Textbook page 12  Tasks 14-15  14 a) 5m 25cmb) 1m 55cm  15 a) 9m 32cmb) 3m 79cm  c) 8m 30cmd) 6m 46cm  e) 3m 20cmf) 9m 1cm  g) 6m 15cmh) 5m 24cm  i) 4m 55cmj) 3m 95cm  k) 3m 55cml) 2m 30cm

17. Extra practice and/or Homework  WB pages 9-10  EP 113-114  Review 1B