A problem with the metaphor of 'progress' in learning is that the 'journey' becomes roughly linear:
If that's extended to an individual lesson, students will be making 'progress' through the lesson. They won't all make as much 'progress' as each other.
Some of them have shot forwards, others are tarrying back nearer where they started.
And what to do with them then, in the next lesson? Put those three shoot-aheaders in a separate group? Ask them to hang around for a bit? Teach them and hope the tarriers will keep up?
a story about a hundred ants.
a strange picture:
Solve an unusual problem.
Because maths isn't just forwards, it's sideways too. Maybe it's like this:
Or perhaps it's like this:
But whatever it's like, it's not in a straight line. So when the students go sideways,
make sure to show the ones on the left what the ones on the right did. And the ones on the right should see what the ones on the left did too.