B5 Mathematics · Term 2 Week 5: Ratios and Proportion

Lesson notes

Learning Objectives

Indicator: B5.1.4.1.5 - Use models to explain the result of multiplying a decimal (up to the thousandths) by a whole number

By the end of the lesson, learners can:

Review multiplication of a common fraction by a whole number using shading models.
Convert a decimal up to the thousandths to its equivalent common fraction.
Use grid and number-line models to show the meaning of multiplying a decimal by a whole number.
Apply the standard method of ignoring the decimal point, multiplying the whole numbers, then placing the decimal point correctly.
Justify the placement of the decimal point by connecting the number of decimal places to the model.

This lesson builds on the work done in Term 2, Weeks 2 to 4, where learners described, compared, rounded, and added/subtracted decimals up to the thousandths. It stays within multiplication of a decimal by a whole number only; multiplying a decimal by a decimal is not part of this indicator and will not be introduced.

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Curriculum details

Strand: Number (Strand 1)
Sub-strand: Ratios and Proportion (1.4)
Content standard: B5.1.4.1 - Demonstrate understanding of decimals fractions and strategies for comparing, adding and subtracting decimal fraction
Indicator: B5.1.4.1.5 - Use models to explain the result of multiplying a decimal (up to the thousandths) by a whole number
Suggested placement: Term 2, Week 5 (Week 17 of the year)
Our suggestion, laid out in curriculum order across three terms of twelve weeks. NaCCA does not fix the week, so follow your school's scheme of learning.
Source document note: The official curriculum document has a fault in this entry, so the curriculum text above is transcribed exactly as printed:

exemplars - p.80
Curriculum reference: Mathematics Curriculum for Primary Schools (Basic 4-6), 2019, p. 80
Transcribed from the official NaCCA publication. Check this page against the source.

Exemplars (from the NaCCA curriculum)

E.g. 1 Review multiplying a fraction by a whole number. e.g. 2/5 x 10 means shade 2 x (1/5 of 10); i.e. 2x(2) = 4;
E.g. 2 To multiply a decimal fraction by a whole number, change the decimal number to common fraction and multiply e.g. 0.4 x 10 means (4/10 of 10) = 4.0; Or multiply the whole numbers 4 and 10, and place the decimal point at one decimal place, since 0.4 has one decimal place
E.g. 3 To multiply a decimal fraction (up to thousandths) by a whole number, first ignore the decimal point and multiply the whole numbers, check the number of decimal places and place the decimal point The fractions are stacked and are written inline.