NCERT Ganita Prakash, Class 8, textbook pages 218–247 (Part 1)

How to teach Class 8 Maths Chapter 7, Proportional Reasoning-1, at home

Ratio, proportion and scaling, taught with things you already have at home: a 30-minute activity, a game for the week, a 5-day plan and the mistakes to watch for.

6 × 49 × 6same ratio 3 : 2

NCERT Class 8 Maths Chapter 7 Proportional Reasoning-1: what it teaches

When a photo is resized, width and height change in the same ratio. Your child writes ratios, recognises proportional relationships, uses the unitary method, and scales recipes, maps and images.

Why it matters later. Proportion is used in percentages, speed, similar triangles and science.

See it: this chapter in pictures

12 : 18÷ 6= 2 : 3
Divide both by the HCF.
4 pens = ₹601 pen = ₹157 pens = ₹105
Find one, then multiply.
map: 1 cm = 5 km7 cm on map= 35 km real
Scale factor turns map distance into real distance.

You need

  • a recipe
  • a map with a scale
  • a phone photo

Tonight’s 30 minutes

  1. Compare a photo’s width and height before and after resizing: is the ratio the same?
  2. Simplify ratios: 12 : 18 = 2 : 3.
  3. Scale a recipe for 4 people to 6 people.
  4. Use a map scale: 1 cm = 5 km. How far is 7 cm?

Words to use

  • ratio
  • proportion
  • unitary method
  • scale
  • equivalent ratios

Watch for

  • Adding instead of multiplying when scaling. If 4 people need 2 cups, 6 people need 3 cups, not 4.
  • Ratio order mixed up. Keep the order: boys : girls ≠ girls : boys.

What it sounds like at home

A short example of the conversation. Your words will differ; the questions are what matter.

YouRecipe for 4 needs 2 cups. For 6?

Your child1 cup for 2 people, so 3 cups.

A game for this week: Scale it

  1. Pick a recipe card.
  2. Roll a die for the number of people.
  3. Scale every ingredient.
  4. Check proportionality together.

A 5-day plan, 30 minutes a day

  1. Day 1Photo ratios.
  2. Day 2Simplify ratios.
  3. Day 3Recipe scaling.
  4. Day 4Map scales.
  5. Day 5Scale it game.

Everyday moments to practise

  • Recipes.
  • Maps.
  • Photo resizing.
  • Mixing paint or juice.

Quick check

Ask these at the end of the week. Tap to see the answer.

Simplify 12 : 18.

2 : 3.

4 pens cost ₹60. Cost of 7?

₹105.

Map 1 cm = 5 km. 7 cm = ?

35 km.

Ready for the next chapter when your child…

  • Writes and simplifies ratios.
  • Recognises proportional situations.
  • Solves by the unitary method.

Activities, wording and illustrations are Mathify Kids’ own, following the topics of NCERT’s Ganita Prakash (Class 8). See the full Class 8 parent guide for every chapter.

Questions parents ask

What is a proportion?

Two ratios that are equal, like 2 : 3 = 4 : 6.

What is the unitary method?

Find the value of one, then multiply.

Why do stretched photos look wrong?

Width and height were not scaled in the same ratio.