Book 29, Question 126
How do you run a fair experiment in the garden?
Start with a question, like "Does compost help beans grow taller?" Plant the same kind of seed in identical pots with the same soil, water, and light.
Change only one thing, such as adding compost to half of the pots. Label everything, measure at regular times, and write down results. Repeat with several plants, because a single plant might be unusual.