Common misconceptions › Class 8 › Maths › Fractions in Disguise Class 8 Maths · Chapter 8 · NCERT (hegp201)
Fractions in Disguise: common misconceptions
See the tempting mistake students make in Fractions in Disguise, why it feels right at first glance, and a worked visual example that shows the right idea.
Worked visual “If your child says…” (8) Teach & practice The tempting mistake & worked visual Does a percent already give a count? Wrong
A 25% discount always means 25 rupees off.
Why it feels right. I read 25% as a fixed amount.
Right
A percentage is a share of a specified whole.
Worked example
25% of ₹200 50 rupees
25% of ₹400 100 rupees
One quarter is the same fraction of both prices. The higher price has the bigger rupee discount. One quarter of ₹200 is ₹50. One quarter of ₹400 is ₹100. Both discounts are 25%. If your child says… (8 concept checks in this chapter)
As you work through Fractions in Disguise , listen for these everyday misunderstandings and use the prompt alongside each one.
If your child says…
“Five shaded columns means 5%.”
Ask together When you count cells instead of columns, how many shaded parts are there? What’s true Count shaded parts and total parts using the same-sized pieces. If your child says…
“A percentage cannot go beyond 100%.”
Ask together If this whole strip is 100%, what happens when the length extends beyond it? What’s true A length greater than the reference strip has a percentage greater than 100%. If your child says…
“Two heads and three tails means heads are two-thirds of the coins.”
Ask together Are there three coins altogether, or five? What’s true The whole includes both heads and tails. If your child says…
“Both are 50%, so both pieces must be the same size.”
Ask together Did the two starting portions contain the same amount of roti? What’s true Equal percentages can give unequal amounts when the wholes differ. If your child says…
“A 50% rise and a 50% fall cancel.”
Ask together Does the fall remove half of 4 rupees or half of 6 rupees? What’s true The fall takes half of a larger amount than the rise used. If your child says…
“Three pieces always mean 75%.”
Ask together What makes each piece here the same share of the sheet? What’s true Counting pieces gives area shares only when those pieces have equal areas. If your child says…
“The tax calculation gives the whole bill.”
Ask together Where does the original 20 rupees appear in the amount paid? What’s true The percentage calculation gives tax alone; the bill also includes the subtotal. If your child says…
“Where can it land?”
Ask together Which destination completes both the two-square part and the one-square part? What’s true The destination must complete both parts of the move. Use this chapter three ways Previous chapter Proportional Reasoning Next chapter The Baudhāyana-pythagoras Theorem
In the app, your child answers a short check-in with confidence taps, and you see which of these misunderstandings showed up—and which ones are gone.
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