Substrate
Substrate is the food or surface that mold and germs use to live and grow.
A slice of bread sits on the counter for too long. Fuzzy green mold spots appear and spread across the surface. The bread is the substrate — it gives mold a place to land and food to eat. Without it, the mold has nothing to grow on.
Explaining substrate by grade level
Put a piece of bread in a wet bag and wait a few days. Fuzzy spots show up on the bread. The bread gives mold what it needs to grow. Without food like bread, the mold has no way to spread.
Projects that explore substrate
Mold needs a surface to land on and feed from. In this experiment, you place a slice of bread or another food item on a damp paper towel inside a sealed sandwich bag. As the warm moisture builds up, fungi start to colonize the surface — sometimes within just three days. You can also compare different surfaces like bread versus carrots to see which one mold prefers.
Which food in your kitchen grows mold the fastest? In this experiment, you place small pieces of five different foods into separate sealed plastic bags. Keep all bags in the same spot so growing conditions stay the same. The only variable is the food itself. Each day for one week, you photograph the samples and measure the mold area. Some foods offer a better home for mold than others.