High School Biology (Khan Academy)

Khan Academy's high school biology course as a playlist of 83 short videos, most four to eight minutes long. It starts with ecology and natural systems (biotic and abiotic factors, ecosystems and biomes, an organism's range and niche, describing populations) and moves on through the course units on cells, energy, genetics and evolution, with short "creativity break" clips at the end about creativity and careers in biology. Clear diagrams and plain English make it a good companion for class 9 and 10 or O Level biology, or for English-medium students who want a concept explained a second way.