Petri dish
A petri dish is a shallow, round, see-through dish with a lid.
What is it for?
Scientists use it to grow tiny living things like bacteria and mould, and to look at small samples.
How to use it
Keep the lid on as much as you can, and only lift it a little when you need to add something.
🥽 Safety tip: Never open a dish that has things growing in it. Ask a grown-up to throw it away safely.
Fun fact from Fizzy: It is named after Julius Petri, a German scientist who invented it in 1887.
How scientists use it
To grow tiny living things, scientists pour a warm, jelly-like food called agar into the dish and let it set. When a few bacteria land on the agar, they feed and multiply into spots called colonies, which are big enough to see without a microscope.
Scientists also use petri dishes to watch seeds sprout, to let liquids dry out into crystals, and to hold small samples under a microscope.
A famous petri dish
In 1928 the Scottish scientist Alexander Fleming noticed that a mould growing in one of his petri dishes had stopped the bacteria around it from growing. That mould led to penicillin, one of the first antibiotic medicines, which has saved millions of lives.