Python: Selection and Iteration | Year 9 Computing PowerPoint Lesson

This lesson teaches the two programming constructs pupils use most. It starts from sequence, selection and iteration as the complete set, then covers if, elif and else with correct colons, indentation and branch order, comparison operators, and the and, or and not Boolean operators. Iteration is taught as a genuine choice between count-controlled for loops with range and condition-controlled while loops, with the three-part rule that prevents infinite loops. Trace tables are taught as a method for locating logic errors, with a worked example. A misconception slide tackles the frozen while loop, and a code-quality slide covers naming, commenting and testing habits. Two activities follow: a five-program debugging challenge covering named syntax and logic errors, and building a number guessing game from a written plan. It is a ready-to-teach PowerPoint scaffold for an hour-long lesson on selection and iteration in Python. British spelling and UK National Curriculum KS3 Computing throughout.