Algae
Algae is a group of small, plant-like life forms that grow in water and make their own food from light.
Algae are like green bits floating in a bowl of water left near a sunny window. The water soaks up the light, and the green bits use that light to grow and spread. A clean bowl stays clear, but one near the sun fills up with floating green specks over time. Each speck makes its own food from sunlight, just like algae do in a pond or ocean.
Explaining algae by grade level
You can find green, slimy stuff in ponds. That green film is algae. Algae live in water and use the sun to make food. If pond water has too much plant food in it, algae grow fast and take up all the air.
Projects that explore algae
Algae grow in water and make food from light — and phosphate feeds that growth. When too much algae accumulates, it can deplete the dissolved oxygen that fish need to breathe. This experiment fills eighteen jars with tap water and algae, then adds increasing amounts of a phosphate solution to most of them. Three jars get no phosphate and serve as the control. All jars go under a grow light, and dissolved oxygen levels get measured each day. The control jars hold the most oxygen, while jars with more phosphate generally show less — even small amounts make a measurable difference.
Not all algae respond to harsh conditions the same way. Some types, like red algae, survive in acidic water, while others like spirogyra die at even moderate acidity. This experiment places spirogyra, green algae, and red algae in water at different pH levels to reveal how each type tolerates acid rain.