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Lesson · Grade 3 · Mathematics

Writing a Fraction: The Top and Bottom Numbers

  • Grade 3
  • Mathematics
  • 1 min 4 s
  • British Columbia
  • BC3-MA-05

A bar is cut into 5 equal parts and 3 of them are coloured. Counting all the parts gives the bottom number, 5, and counting the coloured parts gives the top number, 3. The video writes the fraction 3/5, reads it as three fifths, checks it against the bar and ends on the rule: the bottom number counts the equal parts in the whole, and the top number counts the parts we mean.

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In one sentence

The question this lesson answers

What do the two numbers in a fraction mean?

Here is one whole bar.

Transcript

What the lesson says

What do the two numbers in a fraction mean?

Here is one whole bar.

We cut it into 5 equal parts.

Let's count them: 1, 2, 3, 4, 5.

Now we colour 3 of the parts.

Count the coloured parts: 1, 2, 3.

A fraction has a top number and a bottom number.

The bottom number tells how many equal parts make the whole.

The whole has 5 equal parts, so the bottom number is 5.

The top number tells how many of those parts we mean.

We mean the 3 coloured parts, so the top number is 3.

We read this fraction as three fifths.

Check: 3 of the 5 equal parts are coloured.

The bottom number counts the equal parts in the whole, and the top number counts the parts we mean.

Curriculum

Where this fits

British Columbia, Grade 3

Mathematics, Number: fraction conceptsBC3-MA-05

Previous: A Fraction Is Equal Parts of One WholeNext: A Fraction of a Group

The outcomes and strands follow the British Columbia curriculum.

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