In a class, 1 pupil walks to school for every 3 who get a lift. Roughly what fraction of the class walk? And if the class had 100 pupils, about how many would that be?

The interactive shows three ratios on a battery bar, each as a fraction and a percentage. The filled bar is the first part and the empty bar is what is left. Watch how the two parts of every ratio add back up to 100%, then say which part is bigger in a 3:7 ratio and why, before we check it together.

Now we work three ratios together on the slider: first 1:1, then 1:4, then 3:2. No pencils yet, and nothing to write here — the writing comes next in your copy. For now, just watch the board and say the answers aloud: as a class we say the total number of parts, name the first part as a fraction, then say what percentage it is. A pupil at the board sets the slider to the first part while the rest of us agree or correct out loud, then we read off the empty part and check the two make 100%.