Number: Ratios and Proportion · JHS2 Mathematics

Lesson notes

Learning Objectives

Indicator: B8.1.4.1.2

By the end of the lesson, learners can:

Define a unit rate as a ratio that compares a quantity to one unit of another quantity.
Find the unit rate in a given situation by dividing the first quantity by the second quantity.
Solve unit pricing problems, such as finding the cost per kilogram or cost per item, using division.
Solve constant speed problems, such as finding distance travelled per hour or time taken per kilometre.
Convert between related rates such as kilometres per hour (km/h) and metres per second (m/s), and apply unit rates to compare two or more options and choose the better deal.

Sign in with your phone number to read the full note and download the GES plan - free.

Sign in with phone number

Curriculum details

Strand: Number (Strand 1)
Sub-strand: Number: Ratios and Proportion (1.4)
Content standard: B8.1.4.1 - Demonstrate an understanding of ratio, rate and proportions and use it these to solve real-world mathematical problems. Notes: put a passage for the graph
Indicator: B8.1.4.1.2 - Solve unit rate problems including those involving unit pricing and constant speed; and speed translation.
Suggested placement: Term 2, Week 2 (Week 14 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.
Curriculum reference: Mathematics, Common Core Programme (JHS1-JHS3), 2023, p. 105
Transcribed from the official NaCCA publication. Check this page against the source.

Exemplars (from the NaCCA curriculum)

E.g.1 If it took 7 hours to mow 4 lawns, then at that rate, how many lawns could be mowed in 35 hours? At what rate were lawns being mowed?
• E.g.2Salamatu is a drummer for a band. She burns 756 calories while drumming for 3 hours. She burns the same number of calories each hour. How many calories does Salamatu burn per hour?
Solution
• The ratio of calories burned to hours drumming is 756:3.
• Let's find an equivalent ratio that shows how many calories are burned in1hour.
• A ratio where one of the terms is 1 is called a unit rate. We can divide the number of hours by 3 to get to 1 hour. 756 3
÷3 ÷ 3 ? 1 756 ÷ 3 = 252
Calories burned hours 756 3
÷3 ÷ 3 252 1
Salamatu burns 252 calories per hour of drumming.