NCERT Ganita Prakash, Class 7, textbook pages 134–174 (Part 1)

How to teach Class 7 Maths Chapter 4, Expressions using Letter-Numbers, at home

Introduction to algebra: variables and expressions, taught with things you already have at home: a 20-minute activity, a game for the week, a 5-day plan and the mistakes to watch for.

n squares: 3n + 1 sticks

NCERT Class 7 Maths Chapter 4 Expressions using Letter-Numbers: what it teaches

Letters can stand for numbers. Your child writes expressions like 5a + 3 for a situation, finds their value for given numbers, spots patterns and writes general rules, and simplifies expressions by combining like terms.

Why it matters later. This is the start of algebra, used in equations (Part 2 Chapter 7) and all later maths.

See it: this chapter in pictures

p pens at ₹12, 1 notebook at ₹4012p + 40p = 5 → ₹100
Letters stand for any number.
3x + 5 + 2x − 1(3x + 2x) + (5 − 1)= 5x + 4
Combine like terms only.
n1 2 3 4sticks: 4 7 10 13
A table reveals the rule.

You need

  • matchsticks
  • paper and pencil
  • a price list

Tonight’s 20 minutes

  1. Matchstick pattern: 1 square uses 4 sticks, 2 squares 7, 3 squares 10. Write a rule for n squares (3n + 1).
  2. Write an expression: cost of p pens at ₹12 and one notebook at ₹40 (12p + 40).
  3. Find its value when p = 5.
  4. Simplify 3x + 5 + 2x − 1 = 5x + 4.

Words to use

  • variable
  • letter-number
  • expression
  • like terms
  • simplify
  • value

Watch for

  • Writing 3n as 3 + n. 3n means 3 × n. Test with n = 4: 12, not 7.
  • Adding unlike terms: 3x + 2 = 5x. Only like terms combine; x’s with x’s, numbers with numbers.

What it sounds like at home

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

YouHow many sticks for 10 squares?

Your child3 × 10 + 1 = 31.

A game for this week: Guess my rule

  1. One player thinks of a rule like 2n + 3.
  2. Others give a number; the player says the output.
  3. Guess the rule after three tries.
  4. Swap roles.

A 5-day plan, 20 minutes a day

  1. Day 1Matchstick patterns.
  2. Day 2Expressions for prices.
  3. Day 3Find values.
  4. Day 4Simplify like terms.
  5. Day 5Guess my rule game.

Everyday moments to practise

  • Taxi fare formulas.
  • Phone plan costs.
  • Recipes for n people.
  • Seating in rows.

Quick check

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

Rule for matchsticks in n squares in a row?

3n + 1.

Value of 12p + 40 when p = 5?

100.

Simplify 3x + 5 + 2x − 1.

5x + 4.

Ready for the next chapter when your child…

  • Writes expressions using letters.
  • Evaluates expressions.
  • Simplifies by combining like terms.

Activities, wording and illustrations are Mathify Kids’ own, following the topics of NCERT’s Ganita Prakash (Class 7). See the full Class 7 parent guide for every chapter.

Questions parents ask

What is a letter-number?

A letter used to stand for a number, also called a variable.

Why use letters?

To write rules that work for every number at once.

What are like terms?

Terms with the same letter part, like 3x and 2x.