Mathematics 5 curriculum guide 2015 I table of contents acknowledgements

5N4 Continued...
Achievement Indicator:

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155
MATHEMATICS 5 CURRICULUM GUIDE 2015
Suggested Assessment Strategies
Resources/Notes
MULTIPLICATION
General Outcome: Develop Number Sense
Authorized Resource
Performance
• Ask students to model the following using base ten blocks.
32 × 4 = (30 × 4) + (2 × 4).
(5N4.3)
Paper and Pencil
• Ask students to determine 68 × 7 and explain their method.
(5N4.3)
Lesson 6: Multiplying Numbers 
Close to Ten
TR: pp. 34–37
SB: pp. 194-197
Math Focus 5

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156
MATHEMATICS 5 CURRICULUM GUIDE 2015
Specific Outcomes
MULTIPLICATION
Suggestions for Teaching and Learning
Students will be expected to:
Number
5N2 Use estimation strategies, 
including:
• front-end estimation
• compensation
• compatible numbers
• rounding
 in problem-solving contexts.
Estimation is valuable because it helps judge the reasonableness of an 
answer acquired using pencil and paper or calculators. It can be done 
quickly using tools which are always readily available. An estimate is 
often all that is required to make an important decision. Estimating 
is producing an answer that is “good enough” for the situation, and 
some situations call for more accurate estimates than others. Discuss 
with students situations in which an estimate would be appropriate and 
instances where it would not.
5N2.7 Provide a context for when 
estimation is used to: 
• 
make predictions
• check the reasonableness of an

answer 
• determine approximate
answers.
5N2.8 Describe contexts in which 
overestimating is important.
5N2.2 Determine the 
approximate solution to a given 
problem not requiring an exact 
answer.
Provide students with problem-solving contexts requiring the 
multiplication of two two-digit whole numbers such as:
To raise money at school, 24 students each sold 36 chocolate bars. 
Estimate how many chocolate bars the students sold. 
Through discussion, students should conclude that the operation used 
in this problem is multiplication. Ask students to estimate the product 
using front-end estimation or compatible numbers. Remind students 
that front-end estimation uses only the first digit in each number and 
replaces the other digits with zeros; therefore, 24 becomes 20 and 36 
becomes 30. Review multiplying by 10s and also rewriting each number 
as a product of 10. If necessary, rewrite 20 × 30 as 2 × 3 × 10 × 10 = ?
Students should determine 20 × 30 = 600. 
Students may refine their estimates using compensation. Explain that 
the compensation strategy is used to adjust the estimate to make it closer 
to the actual product. For the example above, ask students whether 600 
is more or less than the actual product and why they think so. A sample 
explanation might be “Since the digits in the ones place were replaced 
by zeros, then 24 x 36 is greater than 600.” Through discussion, 
students should generalize that front-end estimation of the product of 
two numbers is always an underestimate.
When an overestimate is required, or the rounded or compatible 
numbers are not nearby to the originals, students might consider 
rounding one factor in one direction and the other in the opposite. In 
this example, to compensate for the low estimate that would be obtained 
by using front-end estimation, they might instead use 20 × 40 to get the 
closer estimate of 800. 
Encourage students to calculate the answer to the problem using a 
personal strategy and then compare their calculated answer to the 
estimated answer.