Mathematics 5 curriculum guide 2015 I table of contents acknowledgements

66
MATHEMATICS 5 CURRICULUM GUIDE 2015
Specific Outcomes
ADDING AND SUBTRACTING DECIMALS
Suggestions for Teaching and Learning
Students will be expected to:
Number
Achievement Indicator:
5N11 Continued...
5N11.4 (Continued) Solve a 
given problem that involves 
addition and subtraction of 
decimals, limited to thousandths.
Number 
Ones 
Tenths 
Hundredths 
Thousandths 
2.456 
+ 
1.275 
= 
3.731 
To activate prior knowledge, ask students to model a set of decimals 
with base ten blocks. 
Students should begin by determining a sum that does not require 
regrouping, such as 1.213 + 1.124.
Students should then model a sum that requires regrouping, such as 
2.456 + 1.275.
Number Ones 
Tenths 
Hundredths Thousandths 
1.213
+ 
1.124 
= 
2.337 
Kidspiration® software could also be used to help students visualize and 
demonstrate their understanding of regrouping.

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67
MATHEMATICS 5 CURRICULUM GUIDE 2015
Suggested Assessment Strategies
Resources/Notes
ADDING AND SUBTRACTING DECIMALS
General Outcome: Develop Number Sense
Authorized Resource
Performance
• 
For each pair of students, provide base ten blocks, a set of index 
cards with different decimal numbers written on them (such as 1.2, 
2.05, 1.423, 12.3, 4.223), and recording paper.
Ask students to work with a partner. Each person picks one number 
card, models the number selected with base ten materials, and 
sketches the model on a recording sheet. Students should then 
determine the sum of their numbers. They should compare and 
check each other’s sum and the strategy used. 
To further extend this exercise, ask students to:
(i) find the difference between the two
original numbers selected
(ii) choose any three cards and add them
together
(iii) choose two cards and create a word
problem that uses the numbers on both
cards. Exchange problems with another 
pair of students to solve.
(5N11.4)
Observation
• 
Ask students to model a given sum using base ten blocks. Teachers 
should observe:
(i) What strategies do students use to make their numbers? How
do they decide which block will represent one whole?
(ii) How quickly and confidently do they represent and add
decimal numbers? Are they confident in trading/regrouping
(particularly when zeros are involved)? How engaged are they in
the discussion? What questions do they ask?
(5N11.4)
Math Focus 5 
Lesson 5: Adding Decimals by 
Regrouping
TR: pp. 30-34
SB: pp. 94-97