Grade 4 › G4U05 Fraction Equivalence

GRADE 4 · ALBERTAOUTCOME AB-G4-4N5

L2 · Simplest form: dividing by a common factor

Learning goal

“I can write a fraction in simplest form by dividing the numerator and denominator by the same common factor - the amount stays the same, and the point on the number line does not move.”

Common factor — a number that divides evenly into two numbers, like 2 for both 6 and 10.
Greatest common factor (GCF) — the biggest common factor of two numbers.
Simplest form — a fraction whose numerator and denominator have no common factor except 1. Exactly one of a fraction's many names is in simplest form.
Simplify — to rename a fraction in simplest form by dividing both numbers by a common factor.
Worked example

Write 8/12 in simplest form. Step 1: Look for a factor that 8 and 12 share. Both can be divided by 2 - and by 4. Step 2: Divide both numbers by 2 first: 8 / 2 = 4, 12 / 2 = 6, so 8/12 = 4/6. The amount did not change. Step 3: 4 and 6 still share a factor of 2. Divide again: 4 / 2 = 2, 6 / 2 = 3, so 2/3. Step 4: 2 and 3 share no factor except 1, so 2/3 is the simplest form. Model both ways, side by side: a bar in twelfths with 8 shaded, regrouped into sixths (4 shaded), then into thirds (2 shaded) - same shading every time - AND the 0-2 number line where 8/12, 4/6 and 2/3 are one single point. Say it plainly: simplifying is partitioning in reverse - the parts get bigger and fewer, in the same balance.

Check yourself — explain it

Why must BOTH numbers be divided by the same factor?

Paired problem — example still visible

Write 6/9 in simplest form. -> Divide both by 3: 2/3

Faded completion — last step is yours

"10/15 in simplest form: divide both by 5 -> 10 / 5 = 2 and 15 / 5 = ___." -> 3, so 10/15 = 2/3

Ready to practise?

10 scored questions with a 3-rung hint ladder. Mastery needs 8/10 plus both gate questions.