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Class 7 Maths · Chapter 8 · NCERT (gegp108)

Working with Fractions: common misconceptions

See the tempting mistake students make in Working with Fractions, why it feels right at first glance, and a worked visual example that shows the right idea.

The tempting mistake & worked visual

Must multiplication make a fraction larger?

Wrong

½ × ⅔ must be bigger than ⅔.

Why it feels right. Multiplying by whole numbers above 1 makes quantities grow.

Right

Multiplying a positive amount by ½ takes half of it.

Worked example

The full strip has six equal pieces. Two thirds covers four. Half of those four covers two, or one third of the whole.
  1. Shade two thirds of a strip.
  2. Take half of that shaded area.
  3. One third remains selected.

If your child says… (8 concept checks in this chapter)

As you work through Working with Fractions, listen for these everyday misunderstandings and use the prompt alongside each one.

1. Multiplying a Fraction and a Whole Number See how to teach this step →

If your child says… “I multiply both the top and bottom by 6.”

Ask together
Does taking more thirds turn them into smaller parts?
What’s true
Multiplying adds more thirds without changing their size.
2. Multiplying Two Fractions See how to teach this step →

If your child says… “I add the top numbers and add the bottom numbers.”

Ask together
Do two rows of four cells give six cells or eight?
What’s true
Multiply selected rows by selected columns, and total rows by total columns.
3. Cancelling Common Factors See how to teach this step →

If your child says… “I can cancel only numbers that match.”

Ask together
Can both 2 and 4 be divided by 2?
What’s true
Unequal numbers can share a factor.
4. Comparing the Product with the Numbers Multiplied See how to teach this step →

If your child says… “Multiplying by a fraction always makes things smaller.”

Ask together
Is three halves more than one copy of 6?
What’s true
A positive amount shrinks below one copy, stays at one, and grows above one.
5. Division of Fractions: Reciprocal and Brahmagupta’s Formula See how to teach this step →

If your child says… “I turn both fractions upside down.”

Ask together
Did one half need turning over to remove the two-thirds multiplier?
What’s true
Only the divisor turns over when division becomes multiplication.
6. Dividend, Divisor and the Quotient See how to teach this step →

If your child says… “Starting with a small fraction must give a smaller answer.”

Ask together
Does starting with one half prevent an answer of 1?
What’s true
For positive numbers, divisors below 1 enlarge answers, above 1 shrink them, and 1 preserves them.
7. Some Problems Involving Fractions See how to teach this step →

If your child says… “The bigger number must come first in division.”

Ask together
Are we sharing two rotis or half a roti?
What’s true
The amount being shared comes first, even when it is smaller.
8. Fractional Relations See how to teach this step →

If your child says… “One third for later means one third of twelve.”

Ask together
Which peanuts are still available after the snack portion leaves?
What’s true
The later share comes from the six remaining peanuts.

Use this chapter three ways