Louis Pasteur

Hook and introduction: Did you know tiny invisible germs were behind many illnesses and spoiled foods - and one scientist showed how to stop them? Louis Pasteur was a French scientist in the 1800s who proved that germs make us sick. That idea, the germ theory, changed the world.

The experiments: Pasteur boiled broth in special swan-neck flasks to show that life does not appear by magic. The curved neck kept dust and germs out, proving germs from the air cause growth. This clever test helped end the idea that life just appears on its own.

Pasteurization and food safety: He discovered that gently heating milk, wine, and other drinks could kill the bad microbes but keep the taste. This process, called pasteurization, made food and drinks safer and helped farmers and brewers keep products from spoiling.

Vaccines and saving lives: Using the germ idea, Pasteur developed vaccines by weakening germs so the body could learn to fight them. He created vaccines for animal diseases and the famous rabies vaccine, which helped save people from deadly infections.

Legacy: Because of Pasteur, doctors began cleaning hands and tools, hospitals became safer, food stayed fresher, and vaccines grew into a major way to protect people. His discoveries are still used today to keep us healthy.