Labs
A lab is not a worked example with the numbers left blank. You bring the question, or you take the reading; either way you decide what to try, and the record keeps what you did — including the conjectures that turned out to be wrong and the measurements that came out badly, which are the ones worth having made.
Your work is saved on this device as you go, so you can close the page and pick a lab up where you left it. It is not on your account yet — another device starts fresh.
Triangle centres
5 stagesBuild the classical centres of a triangle from medians, perpendicular bisectors and altitudes, then move the vertices and see what survives.
Open this labStages in any orderThe random-walk lab
5 stagesTake a step left or right at random, many times over, and find out how far from the start that actually gets you.
Open this labStages in any orderThe Collatz explorer
5 stagesHalve it if it is even, triple it and add one if it is odd. Follow the rule, survey a range, and meet a question nobody has answered.
Open this labStages in any order