LESSON 2 Activity 1

Stream Characteristics

Grades:

4th - 7th

Objective:

Students learn to make informed decisions about the health of a stream. They learn how to measure temperature, depth, width, pH, and dissolved oxygen using the metric system.

Method:

Students will practice taking water chemistry measurements in an imaginary stream in the classroom, which are the same as the measurements they will later make on the stream field trip. By learning the procedures and discussing the results, students will be more prepared when they are at the stream.

Materials:

Photocopies for each student: Physical & Chemical data sheet, Wind Scale / Percent Saturation data sheet .
Overheads: Physical & Chemical Data Sheet, % Saturation, Wind Scale.

Meter stick
Measuring tape, 30 meters long with metric units, or a cord marked at one-meter intervals.
2 thermometers (with °C)
Dissolved oxygen test kit (either Ward's Snap Test or LaMotte kit, depending on grade level)
pH test kit (either pH paper or LaMotte kit, depending on grade level)
Two plastic bottles: one with hot tap water, one with cold water.
A few ounces of white vinegar
4 clear plastic cups (8oz.)
4 large (16+ oz.) glass jars, prepared as follows:

Time:

Preparation Time: 45 minutes
Class time: 60 minutes

Procedure:
  1. Ask the class: We use our five senses to learn about things around us, like streams. Characteristics are pieces of information that describe an object or place, such as a stream. How might one person describe a stream to another? What are some characteristics that we could use to describe a healthy stream?

    What are data? Tell students they will use a data sheet to record data (characteristics) that describe the stream. Ask: Why would we want to write the information down?

  2. Hand out copies of the Physical & Chemical Data Sheet to the class. Fill in the heading with the class and explain why the location is important (so anyone reading the data will know what stream and what part of the stream are being described). In the remaining steps, students will complete the data sheet using data obtained in the classroom.

  3. Weather Conditions: Ask how these might affect a stream.

    Air Temperature. Explain that we use °C because the scale (0°C = freezing, 100°C = boiling) is easier to remember than F. Also, most thermometers in F have a mark for every two degrees, while Celsius thermometers have a mark for every degree, making them easier to read. Have a volunteer measure the room temperature. Write it on the data sheet.(Optional: Students can practice reading a thermometer by marking the air temperature on the thermometer illustrated on the data sheet. Some students might need help.)

    Wind Scale. Using the overhead of the Wind Scale, have students read each numbered item aloud. Then have two students go to the window and determine the correct number on the scale. All students should record this number on their data sheets.

    Cloud Cover. Ask what is percent? Using a clear cup, point to different levels and have students guess what percent full the cup would be. Once they understand, have two students look out the window and see what percent of the sky is covered with clouds.

    Precipitation. What is precipitation? Talk about how yesterday's precipitation can affect today's stream characteristics. Fill in the correct boxes.

  4. Physical Data: These physical data describe the stream itself.

    Water Temperature. Pour cold water into one cup and warm water into another. Put a thermometer in each. Ask students why we would want to measure temperature when talking about a stream's health. Some animals like cold water (trout, stonefly nymphs), but others like warm water (carp, dragonfly larvae). Have two volunteers come up and read the temperatures (°C). Discuss the freezing and boiling points of water in C compared to F.

    Depth. What tool do we use to measure depth? What units? How many centimeters are in a meter? Tell the class that the classroom has now become a stream, and the level of the water is up to the top of their desks. Have a volunteer measure stream depth (in meters).

    Width. What tool do we use to measure width? What units? The stream is still flowing through the classroom. Have two students measure the width of the stream. Record the data in the metric system, to the nearest centimeter. Inform students that there are two ways to record measurements in the metric system: e.g., 1m 25cm is the same as 1.25m.

    Turbidity & Color. These characteristics are familiar to students, but the terminology is new. Turbid simply means cloudy. Cloudiness is caused by tiny solid particles. Use the four jars to demonstrate that cloudiness and color are independent. Show the plain water first and ask the class to tell you the color and the turbidity. Proceed with the others in the same manner. Explain that if they can see through the water (see your fingers behind the jar), then the water is not turbid. When asked if the tea and muddy water are both the same color, students should say they are both brown, but the tea isn't turbid.

  5. Chemical Data. This section deals with the chemical make-up of stream water.

    Dissolved Oxygen (DO). What do we breathe? What part of our body do we use to breathe? What do fish breathe? What part of their body do they use? Air is 23% oxygen. How much oxygen is in water? About 1/1000 of 1%, or 10 parts per million (ppm). What are ppm? One unit out of every 1,000,000 units. One second in 12 days of your life or 1 inch in 16 miles. Oxygen gets into water in several ways. Two ways are through photosynthesis and by air mixing with water (like when water splashes over rocks). DO is generally higher in riffles and lower in pools of water. Cold water can hold more oxygen than warm water. 12ppm is common in cold water, while 6ppm may be found in warm water. Nine or more ppm is considered healthy. Perform the dissolved oxygen test that you have chosen by following the instructions in the test kit. If you use the snap test, have the students come to a consensus on the color in the tube and record the ppm. It may be best to have students only observe while you perform the Lamotte test. Discuss the results.

    Oxygen Saturation. Place the Oxygen Saturation chart on the overhead. Explain that this chart will tell how saturated with oxygen the water is. Does it have all the oxygen it can hold? The water can be supersaturated (above 100%) only for a brief time. To use the chart, draw a straight line from the water temperature to the dissolved oxygen. The point where the line intersects the % saturation scale indicates the oxygen saturation.

    Acidity (pH). What is an acid? (lemon juice, vinegar) What is a base? (bleach, drain cleaner) Explain that the pH scale ranges from 0 to 14, from acidic to neutral to basic. What can cause high levels of acidity in streams? (acid rain due to car exhaust and industrial pollution) A healthy stream's pH is between 6.5 and 8.0. Prepare two cups of water, one plain, and the other with about 30% vinegar. If you are using pH paper, have a student dip the paper in each sample and match the colors to the comparison chart. If using the LaMotte kit, do the procedure yourself and then have the class decide on the pH. Explain that in the field, at least two tests of pH and dissolved oxygen will be performed, and the average will be taken. This allows a more representative stream sample. (Optional: Before testing the pH, allow a student to taste the vinegar water. Ask students to describe the acid and ask what it would be like for fish to live in it all the time.)
Assessment:
  1. What types of pollution might change some of the stream characteristics such as color, turbidity, and temperature? Be sure to discuss sediment due to erosion.

  2. Most pollution cannot be seen in water - for example, the vinegar used with the pH test. What is another way you could check for vinegar pollution in the water? (smell, taste)

NYS Learning Standards:

English
Standard 1 - Language for Literary Information and Understanding: Listening and Reading

Math, Science, and Technology
Standard 3 - Mathematics: Measurement; Uncertainty
Standard 4 - Science: Physical Setting 2,3
Standard 6 - Interconnectedness: Magnitude and Scale


Source: Activity devloped by Nathan Chronister and Aaron Bennett.