Investigating River Flow: Calculating the discharge of a stream.

Heidi Hilliard, Century Middle School, Lakeville, MN, based on the stream activity from TIMES XIII summer course.

Summary

Before going to the stream students will need to understand depth, velocity and discharge. Students will at first be given minimal instruction and no materials. Students will be asked to try and decide the velocity and depth in order to calculate the discharge. Once they have an estimate with minimal instruction and materials students will meet back together to discuss the various ways they figured out the discharge. Each group will share their method with the class. Each group will then be given an orange, tape measure and a meter stick. They will again calculate the discharge of the stream. When done they will compare their first estimate with no materials with their second estimate in which materials were given to them.

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Learning Goals

This activity is designed for students to use observational and field techniques in order to discover characteristics of a stream.

Students will be able to measure velocity in a stream.

Students will be able to calculate discharge of a stream given certain data points.

Vocabulary Words: Discharge, Velocity, Depth

Context for Use

This activity is designed for 8th grade. This specific field investigation should be done with a class size of students (25-32). You will need access to a flowing stream that is safe enough for students to be in. This is a field exercise, which requires approximately 1.5-2 hours of time to complete. You will need access to enough tape measures, meter sticks and oranges for groups of four. Students need a moderate level of instruction on velocity and discharge, but not too much. Most of what they need to know about these concepts they will figure out during the investigation. This activity is part of the Minnesota Science 8th grade standards. In order to complete this activity with a larger group of students I suggest making it interdisciplinary and having stations. Maybe a station in which students discover the history of that stream, a writing station, a math calculation station and of course a lunch station. These would be in addition to the station in which they are doing the river activity.

Description and Teaching Materials

*When students first get to the river they should make observations on the different characteristics; speed of flow, erosion rates, depth, sand bars, banks.

*They should write down ten observations in their journal. Students would need about 20 minutes to do this, you will have to gauge based on your group of kids.

*When it seems that everyone is done gather them over to discuss what they noticed about the river.

*Have one student or you be in charge of recording these things on a portable white board so everyone can see.

*After you have discussed what they noticed by looking students are going to enter the river/stream with no materials to do some estimating.

*Ask students to use their prior knowledge and whatever else they might need to calculate the discharge of the stream/river.

*Give them as much time as you think they are using productively. Be sure to walk around and ask the various groups what they are doing to calculate the information, and how they are gathering the data.

*When groups are done ask them to leave the stream so the class can discuss the various methods that were used along with the different answers.

*Discuss all of the methods that were used as a group, be sure to write summaries on a portable white board so everyone can see the different ideas.

*Once all ideas have been shared and discussed introduce students to the various materials that they are now allowed to use for the second round of calculations.

*Students should be given an orange, meter stick and tape measure.

*Students can use these materials however they see fit to again try to calculate the discharge of the stream.

*Give students as much time as you see fit. Be sure that they have one student recording their process, so they will be able to share in the end with the class their method and calculations.

*Once students are complete they should meet back together to discuss the results of each group.

*Each group needs to share again their method and answer.

*Once each group has shared student should write in their journal about how they would do it differently if they were given a chance to do it again. Maybe also what other materials would they find useful.

*Student could also be given additional information at this time about the history of this stream/river and how its velocity and discharge may change over time.

Teaching Notes and Tips

Students need clothing that can get wet, especially shoes. Clear guidelines and expectations need to be set with the students as far as water behavior and safety. In the past I have used stream tables to meet this standard. I am hoping that taking students to an actual stream will increase their retention and motivation.

Assessment

Students will be required to complete a lab report that describes what was discovered at the stream using the following format:

Initial observations of river:

Initial method to find discharge:

Second method to find discharge with materials:

What would you do differently if you were to do this again?

Standards

8.3.2.3.1 Describe the location, composition and use of major water reservoirs on the Earth, and the transfer of water among them.

References and Resources