In the summer term, after their Scratch unit in computing, Year 4 pairs spend three lessons building a working model of water changing state, on class accounts managed by the teacher. The starter project gives them a container, a temperature slider running from minus 20 to 120, a particle sprite that makes 24 clones of itself in rows, a block that sends a clone back to its own place, and the two temperature checks ready-made, leaving three empty gaps: below 0, from 0 to 100 and above 100. Pairs write what a particle does in each gap, such as jiggling on the spot, gliding slowly around the bottom of the container, or moving fast and bouncing off every wall. Another pair then drags the slider up and down hunting for things real water never does, such as a gas that stays spread out when it is cooled or ice whose particles have wandered out of their rows, and the authors rework their rules. In the last lesson pairs change the two numbers to model mercury, which melts at minus 39°C and boils at 357°C, and tell the class one way their model is unlike real water.
This page is one of a growing set of PICRAT examples by cell, subject and grade. Page maintained by Andy Perryer.