Problem
Reasoning · Grade 3-2 Size of Fractions
Decide the shape of the fraction
Improper means the two-digit part is the numerator.
Knowing what 'improper' means tells us the big number has to be on top, which cuts the search in half before we even start listing.
3.NF.A.3Make A Systematic ListAn improper fraction needs the larger card on top, which cuts the search in half before any listing starts.
Why?
The bottom card names how many equal pieces make a whole and the top card counts them, so reaching a whole needs at least as many pieces as make one.
Why?
Every arrangement with the smaller card on top is thrown out at once, so only half the pairings ever need testing.
List by choosing the single denominator card
With denominator 8 all six stay under 10.
Reading a fraction as 'top divided by bottom' lets us judge size quickly and toss out the ones that reach 10.
3.OA.A.2Guess And CheckFinish the list with the small denominators
Denominator 6 keeps four and denominator 3 only two.
Small denominators make the fraction big fast, so almost all of those land at 10 or more and only a couple survive.
3.OA.A.2Make A Systematic ListWrite the complete list
Denominator 2 fails entirely, leaving 12 in all.
A neat ordered list makes it easy to see we missed none and counted none twice.
3.NF.A.3Make A Systematic ListList every choice in a tidy order and you will never miss a fraction or count one twice!
- Decide the shape of the fraction
- List by choosing the single denominator card
- Finish the list with the small denominators
- Write the complete list