Changing  +  to  – Whiteboard exercise Play

Changing  –  to  + Whiteboard exercise Play

Correction for short-sightedness Animation Play

Factor out the common factor – reversing a sign Student activity Play

Negative numbers Animation Play

Operations on integers Student activity Play

pH and the concentration of hydrogen ions Animation Play

Reversing a sign Animation Play

Simple calculations on the calculator Animation Play

Subtraction of two vectors Animation Play

The concept of pH Student activity Play

Thermometer Whiteboard exercise Play

Vector subtraction Student activity Play

Why are negative numbers necessary? Student activity Play