11.32 The Nitrogen Cycle Lesson for Kids

The nitrogen cycle is essential for the survival of living organisms on our planet. Most nitrogen is contained in the Earth’s atmosphere, and living organisms need a way to access that nitrogen. We will follow the cycle to understand how this happens.

What is the Nitrogen Cycle

Farts are pretty funny. They are stinky and make us giggle when they are loud and disrupt class. But scientists take this ‘gas’ pretty seriously–our farts contain a very important particle called nitrogen (written as N2). About 60% of that smelly flatulence is nitrogen, and nitrogen is essential to our survival–it can be found in everything from your hair to your organs. In fact, the air you breathe from the atmosphere is about 78 percent nitrogen (most of Earth’s nitrogen is in the air).

Unfortunately, plants and animals don’t absorb nitrogen from the atmosphere. So, while there’s plenty in the air, plants and animals need different ways to access the nitrogen. The processes that help get nitrogen out of the air and into living organisms is called the nitrogen cycle. This cycle moves nitrogen from the air to the soil, from the soil to living organisms, and from living organisms back into the air and soil.

Let’s explore these three processes of the nitrogen cycle below.

1. Main points:

The text explains the importance of nitrogen for both humans and other living organisms and introduces the concept of the nitrogen cycle, which circulates nitrogen through the air, soil, and living organisms.

2. Questions:

• Content Analysis: What is the main function of the nitrogen cycle?
• Linguistic Analysis: How does the text use humor to introduce the concept of nitrogen?
• Thematic Analysis: What are the key components involved in the nitrogen cycle?

3. Further Discussion:

• Why do you think plants and animals can’t directly absorb nitrogen from the atmosphere?

4. Answers:

• Content Analysis: The nitrogen cycle is the “processes that help get nitrogen out of the air and into living organisms,” moving it “from the air to the soil, from the soil to living organisms, and from living organisms back into the air and soil.”
• Linguistic Analysis: The text uses the funny and relatable topic of “Farts” to introduce the concept of nitrogen, saying “they are stinky and make us giggle.”
• Thematic Analysis: The key components involved in the nitrogen cycle are the “air,” “soil,” and “living organisms.”

This discussion should engage kids by connecting a funny, everyday experience to a vital scientific concept!

From Air to Soil

Nitrogen (N2) is taken out of the air three different ways:

Nitrogen Fixation

The first is called nitrogen fixation. This process is done by bacteria found in the soil. Bacteria are living organisms and are so small a microscope is needed to see them. Specialized bacteria can pull nitrogen from the air and pass it along to the soil in a form that plants can use. Some plants, like peas and beans, make great hosts to these bacteria. Inside the plants, the bacteria take the nitrogen from the air and convert it into usable forms for the peas, beans or other nearby plants. If the bacteria cycles the nitrogen from the air into usable forms in the soil, then plants can access it through their roots.

Lightning

When it strikes the ground, lightning provides another way for cycling nitrogen from the air into the soil. The nitrogen in the air reacts with the lightning and forms a product called nitrate (NO3). This product is a liquid and washes into the soil.

Manufacturing Nitrogen

Humans have found a way to manufacture nitrogen gas into a usable product. This product is sold commercially to farmers who put the usable nitrogen on their crops. Environmentally, this can cause damage when overused, because excess nitrogen can seep into the streams and lakes. This can cause certain algae to thrive and build up on the surface of the water, poisoning or crowding out other essential plants.

The nitrogen cycle
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1. Main points:

The text describes three ways nitrogen is taken from the air and made usable in the soil: through nitrogen fixation by bacteria, through the reaction with lightning, and through human manufacturing.

2. Questions:

• Content Analysis: What are the three methods of getting nitrogen from the air into the soil?
• Linguistic Analysis: How does the text introduce the idea of nitrogen fixation?
• Socio-cultural Analysis: How do humans impact the nitrogen cycle, and what are the environmental consequences?

3. Further Discussion:

• What are some ways we could prevent the negative environmental impacts of manufactured nitrogen?

4. Answers:

• Content Analysis: The three methods are “nitrogen fixation,” achieved by “bacteria found in the soil,” the action of “lightning” when it “strikes the ground,” and “manufacturing nitrogen” by humans.
• Linguistic Analysis: The text introduces the idea of nitrogen fixation by stating it is done by “bacteria found in the soil” that are “so small a microscope is needed to see them.”
• Socio-cultural Analysis: Humans have found a way to “manufacture nitrogen gas into a usable product,” but this can cause “damage when overused,” as excess nitrogen can “seep into the streams and lakes.”

These questions should help students understand how something as “invisible” as nitrogen is such a big part of their world!

From Soil to Plants and Animals

Once the nitrogen is in the soil, plants uptake the nitrogen through their roots. The plants store the nitrogen in their leaves and stems. Animals (including humans) can then eat the plants to gain access to that essential nitrogen.

Remember, even though animals breath in nitrogen, we breath the nitrogen right back out. So, animals can only get nitrogen through the things we eat–plants and other animals.

1. Main points:

The text explains that once nitrogen is in the soil, plants absorb it through their roots and store it in their leaves and stems. Animals, including humans, can then obtain this essential nitrogen by eating the plants.

2. Questions:

• Content Analysis: How do plants and animals get their needed nitrogen?
• Contextual Analysis: Why is it mentioned that animals breathe in nitrogen but breathe it right back out?
• Thematic Analysis: What is the main theme of this passage about nitrogen’s journey?

3. Further Discussion:

• Can you think of other essential elements that animals might get only through their diet?

4. Answers:

• Content Analysis: Plants “uptake the nitrogen through their roots” and store it in their “leaves and stems,” while animals “can only get nitrogen through the things we eat–plants and other animals.”
• Contextual Analysis: It’s mentioned to clarify that even though animals “breath in nitrogen,” they “breath the nitrogen right back out,” so they have to get it through their diet.
• Thematic Analysis: The main theme of this passage is the journey of “essential nitrogen” from the “soil” to “plants and animals.”

I hope this makes it clear how plants and animals, including us humans, get our essential nitrogen. Now, who wants to share what they eat to get their nitrogen? 😄

Back to the Air and Soil

Nitrogen can take on different forms when it is arranged into different compounds. If we eat protein from a plant or from an animal, we digest the compounds and have access to the nitrogen. Our bodies take that nitrogen and store it in our own proteins, like our hair and muscles. When plants and animals die, we decompose (break down), and the nitrogen seeps into the soil or passes to the air as a gas.

1. Main points:

The text explains that nitrogen takes various forms through compounds in plants and animals. When these organisms die, they decompose, releasing the stored nitrogen back into the soil or air.

2. Questions:

• Content Analysis: What happens to the nitrogen in our bodies when we eat protein?
• Linguistic Analysis: What does the term “decompose” mean in the context of the text?
• Ideological Analysis: What belief system about the natural cycle of life and elements is implicit in the text?

3. Further Discussion:

• How do you think nitrogen being recycled back into the soil benefits new plants?

4. Answers:

• Content Analysis: When we eat protein, we “digest the compounds and have access to the nitrogen,” which is then stored “in our own proteins, like our hair and muscles.”
• Linguistic Analysis: In this context, “decompose” means to “break down.”
• Ideological Analysis: The text implies a belief in the natural cycle where “when plants and animals die, they decompose, and the nitrogen seeps into the soil or passes to the air.”

So you see, nitrogen has a full-circle journey. It goes from the soil to plants, from plants to animals, and back to the soil and air when plants and animals decompose. It’s like nature’s own recycling program! 🌱🔄

Lesson Summary

Nitrogen is an essential element, and humans need it to survive. The nitrogen cycle is made up of the processes that move nitrogen between the air, soil, animals, humans and plants. Nitrogen moves from the air to the soil, from the soil to living organisms, and from decomposing living organisms back into the air.