Investigating local stream discharge

Katie Melgaard, New Heights School, Stillwater, MN.
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Summary

This activity's purpose is to introduce hydrology to eighth grade students by investigating stream discharge of a local stream. The students will make observations about the stream, determine the velocity and discharge of the stream, and develop and carry out an investigation regarding the stream and it's flow. Students will, in small groups, present their findings to the rest of the class.

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Learning Goals

Learning Goals: This activity is designed for students to further develop their skills in observing, questioning, experiment design, and data collection. Students will develop writing and oral communication skills as well.

Concepts: Stream discharge is determined by multiplying width, depth, and velocity of stream. Calculated stream discharge should not change based on where along the stream it is calculated. Stream discharge will change depending on precipitation levels.

Vocabulary: velocity, discharge, independent variable, dependent variable

Context for Use

This investigation is designed for 1 eighth grade section in a small charter school with a maximum class size of 25 students. The stream is about a block away and is only a couple inches deep. Students will have already had practice making observations such that 20 observations in a small group isn't overwhelming. This activity will start off my hydrology unit in the spring, which should provide good weather, a flowing stream, and not too much vegetation surrounding/covering the stream. This activity could easily be modified for any local stream.

Description and Teaching Materials

Materials: student notebooks, portable dry/erase board to write questions, meter sticks, corks, stopwatches, topographic maps (1 per student) of area.

As a class, with our notebooks, we will walk the block from the school to the small stream. I'll group the students into groups of 3 students with the direction that each student needs to have 20 observations about the stream in their notebook. Then as a small group, they need to come up with a good description of the stream, which we will share and discuss as a class. Then, as a class, we will come up with questions that we have about the stream. (Should include questions such as "Where is the source?, Where does the water go downstream?, How long is the stream?, How much water is flowing through?, Does the volume of water change over the course of a year?")
Mention that we will be investigating the velocity and discharge of the stream for now. Have the students in their groups come up with an estimate of the velocity of the water flowing.

Second day, walk back down to the stream and discuss what measurements are needed for velocity. Discuss what sort of units we should use (feet/meter/second/minute). Talk to the students about stream discharge (definition). Have the students calculate the discharge using meter sticks and corks. As a class, discuss the results and the brainstorm the questions that are still unanswered. (Was the discharge number calculated the same with every group? Should it be? Should the discharge number vary depending on which section of the stream you test? Should it vary with any other variables?). End with a review of what the students know about this particular river.

Third day, walk back down to the stream and have the students (in small groups) develop an investigation that they can perform (within materials and time guidelines) on the stream and it's flow. Each student will have the proposed investigation approved by the teacher. Time is given to complete the experiment and record results in notebook.

Fourth and fifth day, finish up getting the data needed for student investigation. Each group should record their results on a white board and be ready to present to the class. As students have down time, have them look at a topographic map of the neighborhood and discuss with the students why the stream is or isn't on the map. The students should draw in where the stream should be and notice any features about the area (low elevation). With any more down time, talk about weathering and erosion in this particular area. Have the students investigate the rocks and discuss why they are all rounded.

Sixth day, have the student groups present their findings to the class. Teacher should ask questions such as "What would you do now" and clarifying questions that help the students think beyond their individual investigation. If any student groups used independent (controlled) and dependent variables, they should be pointed out by the teacher. Students should ask any questions they have to the presenting group.

Teaching Notes and Tips

I haven't taught this activity yet, but safety should be mentioned. The stream is a few inches deep during it's deepest, so I am not concerned about student safety. However, I will mention to the students (and send a note home with them) that they should bring water shoes or a spare set of shoes and socks.
Teacher should have little experiments/investigations ready for the groups that get done quickly and be prepared for some investigations to be ongoing (for example, if a student group is investigating the relationship between precipitation and stream discharge).

Assessment

The oral presentations with the written data on the white board will provide good information as to what the students got out of the investigation. I will be probing each student group with questions regarding their investigation and will be able to know how involved they got with it.

Standards

8.1.3.4.2 Determine and use appropriate safety procedures, tools, measurements, graphs and mathematical analyses to describe and investigate natural and designed systems in Earth and physical science contexts.

8.1.3.4.1 Using maps

8.3.1.2.2. weathering and erosion in Minnesota

References and Resources