Mathematics 5 curriculum guide 2015 I table of contents acknowledgements

Achievement Indicators:

---

59
MATHEMATICS 5 CURRICULUM GUIDE 2015
Suggested Assessment Strategies
Resources/Notes
ADDING AND SUBTRACTING DECIMALS
General Outcome: Develop Number Sense
Authorized Resource
Note
This strategy of estimating to 
ensure proper placement of the 
decimal is merely mentioned in 
Math Focus
Lesson 5. Teachers 
should use examples from this 
guide to help students with this 
strategy.
Journal
• Ask students to estimate to match each example from the left to the 
answer on the right and explain their reasoning.
(i) 0.713 - 0.522 
4.48
(ii) 4.80 - 0.32
0.631
(iii) 0.229 + 0.402
2.02 
(iv) 2.99 - 0.97 
0.191
(5N11.1) 
• Ask students to describe how to use estimation to determine the 
placement of a decimal in a sum or a difference.
(5N11.2)
Paper and Pencil
• Ask students to estimate the missing number in each example and 
explain their thinking.
(i) 0.099 + 0.280 is about ___________
(ii) 2.948 + 5.799 is about ___________
(iii) 18.97 - 4.77 is about ____________
(5N11.1)
• Jane was running in her school’s track and field competition. Her 
first race time was 4.127 minutes. Her second time for the same 
distance was 4.091 minutes. Ask students:
(i) Estimate her total running time. Explain your thinking.
(ii) In which race did she perform better?
(iii) About how much faster was her time for the second race?
(5N11.1)
Performance
• Provide the students with a selection of addition and subtraction 
problems using decimals to thousandths. Include the calculated 
answer without the decimal point. Ask students to decide where 
the decimal point should be placed in each answer and explain how 
they know. Encourage the use of a variety of estimation strategies. 
Students could then share their answers with the whole class and 
correct any errors in decimal point placements.
(5N11.2)
Math Focus 5
Chapter 3: Lesson 3: Estimating 
Decimal Sums and Differences
TR: pp. 22-25 
SB: pp. 88-91

---