Joseph F. Zisk (formerly a high school chemistry teacher) Science Educator California University of Pennsylvania California, PA 15419

Engagement

Capture the students' attention. In this case, a question is asked. The discussion is designed to guide students to make connections between what they know and what they are about to study.

Questions asked to students

Is it possible for river water to have too little or too much oxygen? Why or how?

Students working in small groups outline the answers that they will present to the class. The small group discussion will last for only about 3 minutes. The teacher will provide answers to group questions in a yes/no format.

During the discussion of the students' presentations, the teacher focuses on key concepts that students will need to know in order to move to the next stage. Terms such as unsaturated, saturated, supersaturated, oxygen levels in ppm will need to be developed.

Exploration

Students research data to explore the possibility of an unsaturated, saturated and supersaturated oxygen solution.

Students are asked to analyze data and to plot graphs to look at questionable DO levels (high / lows).

Small groups are formed

Students are divided into small groups of three to four students.

Roles are given to each member of the group:

1) materials person - this person will get all materials

2) recorder - this person will write down any activity design and will prepare a chart for data entry

3) information seeker - this is the only person who will be permitted to ask the teacher a question. All questions must be asked in such a way as to permit a "yes" or "no" response

4) computer specialist - this person is to enter students' responses into the electronic student journal

Each group is given: an activity sheet, graph papers, rulers, tables.

Students are to record their answers onto the activity sheet and each student is to plot a graph.

 

Supersaturation

By looking at the 100% oxygen saturation table (in handout), have students determine the percent saturation. Advise students to select points on the graph that they suspect have high or low DO levels.

 

Explanation

Students are to make sense of their exploration. They are to find patterns and relationships and answers to questions. Students are urged to explain their findings and to demonstrate their understanding.

Students are to prepare an outline of their findings. Based on their analysis of the data (DO, temperature and calculated percent oxygen saturation), students are to determine the possible reason for the fish kill and to propose a theory for the cause of these high levels.

Each group will make a one minute presentation on the possible reasons for high oxygen levels.

Elaboration

Students are given opportunities to apply the concepts and skills that they have acquired to different situations.

Supersaturated oxygen river water may be caused by several reasons. Review several ways in which oxygen enters into water.

Ask the class -- can any of the ways (presented by groups) be the reason for the supersaturated levels?

At this point, the teacher is to introduce the DO kits and provide a brief explanation of how they work and what they measure.

Have students formulate a question, that they can test later, about water becoming supersaturated.

During the next lab activity we will check DO levels of water and determine how to make a supersaturated solution.

In the electronic journals students are to enter: KLW

 

know- what we already knew about DO and fish requirements

 

learned - what we learned about DO and how it can affect life

 

want to learn - formulate a question about unsaturated, saturated and supersaturated levels of DO which can be tested during the lab activity

Students conduct an experiment to explore the possible ways of making an unsaturated, saturated and supersaturated oxygen solution.

Using DO kits, students are to determine DO of water under various conditions. The group is to design an investigation and conduct it using the laboratory equipment available.

Explanation (revisited)

Students are to make sense of their exploration. They are to find patterns and relationships and answers to questions. Students are urged to explain their findings and to demonstrate their understanding.

Collection and presentation of data

Students are to prepare an outline of their findings. Based on their findings and by looking at the map of Riverwood and the location of various objects (dams, water treatment plant, industry, river flow, etc.), they are to form a hypothesis for the cause of the fish kill.

Evaluation

Call upon students to demonstrate their knowledge and understanding of the ideas under study.

Analysis and Interpretation

As a group, answer these questions.

• Propose a reason for the supersaturated oxygen solution
• Is it possible to prevent this problem form occurring again in the future? Explain your answer.

 

What would be some advantages of building a spillway?

As a group, respond to the following statement. In your response, use terms such as DO, temperature, dam, water flow, supersaturated, prevention, "thirty year" rain storms.

When building a new dam, what factors should the designers take into consideration to protect the fish in the river below. Keep in mind, extra construction cost time and money. It is going to cost 20%-30% more to protect the fish. This will cause a sharp increase in our taxes or utility bills. How would you feel about paying more money ($40 a month) if you were laid-off or out of a job?

Present your response to the class. Each group gives a 1-2 minute presentation.

Joseph F. Zisk
zisk@cup.edu

©1998