Archive footage of Sir Alexander Fleming demonstrating how he discovered the world's first antibiotic, penicillin. Fleming discovered the Staphylococcus bacterium could not grow near the Penicillium fungus, which had contaminated his petri dish.
This clip could be used by students to introduce how antibiotics were discovered. It opens with the question: "if you could go back in time how would you describe the effects of penicillin on people's lives today?" It therefore lends itself very nicely to reviewing this question at the end.