A lesson or a homework activity on algorithm design, with AFL, printer-ready (A4), with solutions
Overview of Flowgorithm - a great free program for teaching pseudocode and flowcharts. Will also mention that it can run on MacOS with Wine.
This is the first 70 algorithm problems (with solutions, as well) from the set that we use in our CPD - we have 100 problems in the CPD one. This should get your pupils started and well under way into their algorithmic thinking.