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Class 6 Maths · Chapter 7 · NCERT (fegp107)

Fractions: common misconceptions

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

2 worked misconception examples

Worked example 1 of 2

Can you add the bottom numbers?

Wrong

1/2 + 1/3 = 2/5

Why it feels right. I use the whole-number rule for adding on both rows. One plus one is two. Two plus three is five.

Right

Add equal-sized parts. Here 1/2 + 1/3 = 3/6 + 2/6 = 5/6.

Worked example

The proposed 2/5 is shorter than the 1/2 you started with. The sum fills five sixths.
  1. Split both bars into sixths.
  2. The half fills 3 sixths and the third fills 2 sixths.
  3. Together they fill 5 sixths.
  4. The proposed 2/5 is smaller than 1/2, even though we added a positive amount to 1/2.

Worked example 2 of 2

Can adding one to both numbers keep a fraction equal?

Wrong

2/3 = 3/4

Why it feels right. I add one to both numbers and expect the changes to cancel out, like doing the same thing to both sides of an equation.

Right

Multiply or divide both numbers by the same nonzero factor to keep the fraction's value. So 2/3 = 4/6.

Worked example

Two thirds and four sixths reach the same point. Three quarters reaches farther.
  1. Split each third into two equal pieces.
  2. The same shaded amount now fills 4 of 6 pieces.
  3. On a strip of the same length, 3/4 leaves only one quarter unshaded, while 2/3 leaves one third.
  4. The two amounts differ.

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

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

1. Fractional Units and Equal Shares; Fractional Units as Parts of a Whole See how to teach this step →

If your child says… “The triangle cannot be a half.”

Ask together
Does each shaded section match the unshaded section when folded?
What’s true
The share's size relative to its whole matters, even when its shape changes.
2. Measuring Using Fractional Units; Marking Fraction Lengths on the Number Line See how to teach this step →

If your child says… “Three inside ticks mean thirds.”

Ask together
How many equal spaces do those three inside ticks make?
What’s true
The denominator counts equal spaces within a whole unit.
3. Mixed Fractions See how to teach this step →

If your child says… “A fraction cannot be more than one.”

Ask together
After making a whole roti, what remains on the plate?
What’s true
Counting fractional units can give an amount larger than a whole.
4. Equivalent Fractions; Expressing a Fraction in Lowest Terms See how to teach this step →

If your child says… “A smaller top number means the fraction is simplest.”

Ask together
Can both numbers in two-quarters still be divided by 2?
What’s true
A fraction can simplify whenever a number greater than 1 divides both its numbers.
5. Comparing Fractions See how to teach this step →

If your child says… “The bigger bottom number means more.”

Ask together
Which reaches farther: the half-strip or the quarter-strip?
What’s true
The denominator alone cannot tell which fraction is larger.
6. Addition of Fractions with the Same Fractional Unit or Denominator See how to teach this step →

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

Ask together
Did joining the pieces make each piece smaller?
What’s true
The denominator stays because the size of each fractional unit stays.
7. Subtraction of Fractions See how to teach this step →

If your child says… “I can subtract different bottom numbers directly.”

Ask together
How many quarter-sections does the half-piece cover?
What’s true
Express both amounts in matching fractional units before subtracting their counts.
8. A Pinch of History See how to teach this step →

If your child says… “The half and third already make a whole.”

Ask together
What part remains unfilled if we use only the half and third?
What’s true
The half and third leave a gap that the sixth fills.

Use this chapter three ways