Biodegradation
Biodegradation is when living things like germs and fungi break down waste into soil and simple parts.
A compost bin in the kitchen holds food scraps like apple cores and bread crusts. Tiny microbes and fungi live in the bin and feed on the scraps. They break the scraps into smaller and smaller bits. Over time, the bin fills with dark, crumbly soil instead of food waste.
Explaining biodegradation by grade level
When you bury a spoon made from plants, it starts to rot. Tiny germs in the dirt eat it bit by bit. After a few weeks, it gets soft and falls apart. A plastic spoon stays the same because germs cannot eat it.
Projects that explore biodegradation
Germs and fungi break down food scraps, but cold slows them down. Bury carrot pieces in soil at different temps to see how fast they rot.
Biodegradation works on a timeline. Germs and fungi break down fruit scraps and newspaper in just weeks, but plastic resists breakdown for centuries. A compost column filled with mixed waste shows which items decompose and which stay the same over time.
Products labeled "biodegradable" claim they will decompose, but how fast does that actually happen? Bury corn starch spoons, wheat-based spoons, and regular plastic spoons in moist garden soil for 30 days. Weigh them before and after to calculate the percentage of weight each type lost.