Students explain multiplication estimation methods used to solve word problems.
Curriculum Links:
This resource can help to identify students' ability to apply multiplicative strategies flexibly to whole numbers when estimating the products.
Key competencies
This resource involves recording the strategies students use to estimate a multiplication problem. This relates to the Key Competency: Using language, symbols and text.
Jess
Indicates estimation using
47 × (91 + 9) = 47 × 99
which is less than 47 × 100 = 4 700
because 99 is less than 100. or
Other similar explanations.
[Do not accept arguments based on exact calculations.]
difficult
(for both correct)
Diagnostic and formative information:
Common error
Likely reason
a)
Sam
Rounds 99 to 100 and 47 to 50 to get an estimate of 5 000.