# 6.3: Activities and Answer Keys

Difficulty Level: At Grade Created by: CK-12

## Activity 5-1: Go With the Flow: Hubbard Brook Watershed

### PLAN

Summary Students learn about the role of trees in the cycling of nutrients in a watershed by building a simulated watershed and measuring the effects of deforestation on the amount of nutrients that remain in the system.

Objectives

Students:

\begin{align*}\checkmark\end{align*} explain the cycling of nutrients in a forest.

\begin{align*}\checkmark\end{align*} demonstrate how clear-cutting alters this cycling.

\begin{align*}\checkmark\end{align*} evaluate the validity of using a model to study natural phenomena.

Student Materials

Per student

• Resource 1
• Resource 2
• Activity Report

Per group or class

• 8 to 10 half-liter milk cartons, rinsed and opened; One-liter pitcher; Graduated cylinder; Water; Stapler or tape
• Large tray with sides at least 4 centimeters high (a wallpaper tray or piece of gutter will work)
• 1 Piece of sturdy cardboard approximately 1 meter square

Teacher Materials

• Towels if done indoors
• Bucket or sink to dump any extra water

Ask students to begin collecting half-liter milk cartons a few weeks before the simulation. Make sure they rinse them thoroughly. The pitchers need to hold about a liter of water so the cartons can catch a substantial amount of water.

You may find large pieces of cardboard at appliance stores or in cardboard recycling bins.

For the large tray, you can use a piece of gutter or a wallpaper tray. These items are available at most hardware stores.

Set up a table with all the student materials so students may gather materials as needed. You may want to do this activity outside.

Estimated Time

30 minutes to set up the simulation

15 minutes to run the simulation and record observations

15 minutes to design the deforestation simulation

15 minutes to run the designed simulation and record observations

20 minutes to analyze the graphs and answer the Activity Report questions

Interdisciplinary Connection

Math The graph interpretation portion of this activity could be used in math class as an extended lesson on interpreting double-line graphs. It also demonstrates the relevance of math skills in representing scientific data.

Prerequisites and Background Information

Students should have some introductory information about the cycling of nutrients through a watershed. Students should have the ability to use a graduated cylinder.

### IMPLEMENT

Introduce Activity 5-1 by discussing with students the cycling of nutrients in the environment. Lead them into the activity by asking what a watershed is.

Steps 1-3 Ask students to read pages 26-30. You can do this activity as a demonstration. Or you might wish to divide the class into small groups of 4 to 6 students. If enough materials are available a third option is possible by dividing the class into pairs of students. Regardless of how they are grouped, students should be able to complete the simulation on their own. If necessary provide copies of Resource 1 showing the experimental setup.

Steps 4-6 While students are running the simulation:

• make sure that they pour the water slowly in a steady stream.
• remind them that they will need to measure the amount of water caught in the tray, so they don't want to spill any of it on the floor.
• make sure as they remove the cardboard from the tray to turn the cardboard over and empty the cartons of water into a sink or bucket.

Steps 7-9 When students are ready to design their simulation of a deforested hillside, you might suggest that they draw a diagram of the model. One way to simulate the effect of deforestation is to remove the milk cartons from the cardboard and repeat the rainstorm experiment. Make sure they explain their design and the reasoning behind it on the Activity Report.

Question 6 on the Activity Report offers the opportunity to analyze the simulation and relate it to the cycling of nutrients in a natural community. You may wish to discuss this question with the class and ask students to critique how well this exercise simulated an actual watershed.

Extend Activity 5-1 by doing the graph interpretation portion of this activity in math class as an extended lesson on interpreting double-line graphs. The extension demonstrates the relevance of math skills in representing scientific data.

Step 10 Students analyze a graph of nutrients in the Hubbard Brook watershed. This is an excellent opportunity to review graph interpretation skills. Suggest that the solid line in the graph could represent their simulation data for the forest that was not clear-cut and the dotted line could represent their data for the forest that was clear-cut.

Students may notice that the cardboard gets wet. They might conclude that the water is being lost as the cardboard absorbs it. Ask the students if this is true to the simulation only or if there is an analogy in nature. (It is analogous to nature because it simulates how the soil on the hillside would naturally absorb the rainwater.)

Discuss with the class the impact of deforestation on watersheds. Are there local examples of logging that may cause similar problems?

### ASSESS

Use the students' written answers and discussion of the Activity Report to assess if students can

\begin{align*}\checkmark\end{align*} demonstrate accurate measurement and data collection skills.

\begin{align*}\checkmark\end{align*} describe how nutrients cycle through a forest watershed in the water, trees, and soil.

\begin{align*}\checkmark\end{align*} interpret graphs.

\begin{align*}\checkmark\end{align*} explain how human activities affect the natural cycling of nutrients in an ecosystem.

## Activity 5-1 Go With the Flow: Hubbard Brook Watershed – Activity Report Answer Key

• Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.
1. What is the amount of water in the full pitcher?
2. Describe what you observed while pouring.
3. What is the amount of water collected in the tray?
4. Compare the amount of rainwater in the pitcher at the beginning of the experiment (the full pitcher) with the amount of water you collected in the tray. What happened to the water?
5. What does the water collected in the tray represent in the model?
6. Explain the experiment you designed to represent the deforestation of Hubbard Brook watershed. Use another piece of paper if necessary.
7. What was the amount of water in the full pitcher before you poured it on your deforestation simulation?
8. What was the amount of water collected in the tray after you poured it onto your deforestation simulation?
9. Compare and contrast your data and observations for the amounts of water that were collected in the stream before and after deforestation. Explain your results.
10. Look at the graph of nitrates collected from Hubbard Brook. Was the amount or concentration of nitrates higher or lower in the stream after the hill was clear-cut? Why do you think this was so?
11. Clear-cutting changes the amount of runoff from a watershed and the amount of nutrients in the water. What are two more ways that clear-cutting changes a watershed?
12. People use wood for paper, furniture, fuel, buildings, and many other products. What could be done that might reduce the amount of nitrates lost from a forest but still allow the harvesting of trees?

• Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.
1. What is a watershed?
2. What happens to most of the nutrients, such as water and nitrogen, in a forest that is undisturbed by humans?
3. What happens to these nutrients if all of the trees in the forest are cut down?

## Activity 5-1 Resource 1 Go with the Flow: Hubbard Brook Watershed (Student Reproducible)

Experimental Setup

## Activity 5-1 Resource 2 Go with the Flow: Hubbard Brook Watershed (Student Reproducible)

The solid line represents the amount of nutrients that collected in the stream at the bottom of a watershed on a hillside that was not clear-cut.

The dotted line represents the amount of nutrients that collected in the stream at the bottom of a watershed on a hillside that was clear-cut in 1965-1966.

## Activity 5-1 Report Go with the Flow: Hubbard Brook Watershed (Student Reproducible)

1. What is the amount of water in the full pitcher?

2. Describe what you observed while pouring.

3. What is the amount of water collected in the tray?

4. Compare the amount of rainwater in the pitcher at the beginning of the experiment (the full pitcher) with the amount of water you collected in the tray. What happened to the water?

5. What does the water collected in the tray represent in the model?

6. Explain the experiment you designed to represent the deforestation of Hubbard Brook watershed. Use another piece of paper if necessary.

7. What was the amount of water in the full pitcher before you poured it on your deforestation simulation?

8. What was the amount of water collected in the tray after you poured it onto your deforestation simulation?

9. Compare and contrast your data and observations for the amounts of water that were collected in the stream before and after deforestation. Explain your results.

10. Look at the graph of nitrates collected from Hubbard Brook. Was the amount or concentration of nitrates higher or lower in the stream after the hill was clear-cut? Why do you think this was so?

11. Clear-cutting changes the amount of runoff from a watershed and the amount of nutrients in the water. What are two more ways that clear cutting changes a watershed?

12. People use wood for paper, furniture, fuel, buildings, and many other products. What could be done that might reduce the amount of nitrates lost from a forest but still allow the harvesting of trees?

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