Unit A: Energy and Matter Exchange in the Biosphere

Can carbon offsets help you reduce your environmental footprint, practice sustainable living and fight climate change?

This backgrounder explains what greenhouse gases are and how they contribute to climate change.

Water is a precious natural resource. What happens if it gets polluted? Learn how water can be cleaned with this hands-on activity?

Learn about the chemical reaction that happens between acid rain and limestone.

Biofuels like ethanol might help fight climate change. But they can contribute to food insecurity and greenhouse gases in ways that might surprise you.

The fracking process gets natural gases out of rocks. This process can have effects on freshwater, water quality and even earthquakes!

What is the nitrogen cycle? How do human activities such as using fertilizer affect the nitrogen cycle? How can this cause greenhouse gases?

The ocean is full of very small but very useful creatures called microbes. Without them, none of the sea plants or animals you’ve seen would exist!

Learn how you can write and reveal secret messages in this hands-on chemistry activity.

Learn how to make a pH indicator and test water samples.

How do different populations adapt to their environment? Let’s explore this concept through guppy speciation.

When fertilizers from agriculture get into lakes and rivers, big problems can result for aquatic ecosystems, food chains & webs!

Heavy metal is a term for some toxic chemical elements. They can cause problems like bioaccumulation, but are useful in nuclear medicine and medical imaging.