Mathematics for Teaching Category: Number Sense

## Category: Number Sense

### Free Fractions Pamphlet

I just want to promote in this post James Tanton’s latest pamphlet on fractions. It’s FREE for download. Just click Pamphlet on Fractions. Tanton writes: If fractions are pieces of pie, then what does the multiplication of fractions mean? (You can’t multiply pie!) If fractions are proportions, then what are their units? Amount of pie per…

### Why PEMDAS is ‘morally’ wrong

Here’s a video that explains why you need to memorise PEMDAS (or BODMAS, BIDMAS, depending where you are in the world) order of operation and why you don’t need to. Minute Physics who made this video made a mistake in assuming that PEMDAS is taught in schools without emphasising that multiplication and division should be…

### Why do we ‘invert’ the divisor in division of fractions

The easiest (and the most common) way to teach division of fractions is to just give the rule: To divide 5/8 by 2/3, just multiply 5/8 by the reciprocal of the divisor, 2/3. That is, 5/8 ÷ 2/3 = 5/8 × 3/2 = 5×3/8×2 = 15/16. If this is all we want our students to learn why…