Over two lessons, Year 8 build a working model of their pondweed practical in Scratch, using class accounts managed by the teacher. The teacher provides a stage with a pondweed sprite and two sliders, light and carbon dioxide, each from 0 to 10, and each student writes their own program that releases oxygen bubbles at a rate set by the sliders. Most first versions make the bubble rate climb for ever as the light goes up, so the teacher shows the class's results from last week's practical, where the count stopped rising much once the lamp was close, and students rewrite their rule so that whichever slider is lower sets the rate. Students then swap models with a partner, try to break them with extreme settings, and finish by writing how their program explains the class's results.
This page is one of a growing set of PICRAT examples by cell, subject and grade. Page maintained by Andy Perryer.