[1]
Purposes
- To introduce students to the specific scenario and driving question, which form the basis for this pathway.
- To introduce students to a cross-sectional drawing of the pond that they will add to and revise throughout the pathway.
Description
Share the Mystery at Sunrise Farm Pond with students:
[stextbox id = “info”] Farmers at Sunrise Farm are planting crops for the season. They spread fertilizer on the field. The fertilizer contains chemical nutrients [2] that help the plants grow. Much of the fertilizer is used by the plants or absorbed by the soil, but not all. When it rains, some of the fertilizer goes into the stream by the field and flows into Sunrise Farm Pond.When one of the farmers checks on the pond a few months after planting the crops, she finds that several of the fish have died.
Why are the fish dying at Sunrise Farm Pond?
[/stextbox]Provide time for students to ask questions about the story (for example about unfamiliar ideas or vocabulary) and the driving question (Why are the fish dying at Sunrise Farm Pond?) as needed. Students then make a drawing of what they think might be important for answering the driving question using the pond cross-section template [3].
Questions to Ask Students
- What plants or animals do you think are important to include in your drawing to explain why the fish died?
- What do you think happens to the fertilizer when it goes into the pond?
- How might the fertilizer in the pond lead to dead fish in the pond?
Student Thinking
Some students may believe that fertilizer is food for plants, and maybe even for other organisms. Students may have little basis for relating the fertilizer to fish death. Alternatively, the fish death may reinforce a student’s incorrect idea that all chemical substances humans use are toxic. These students may be especially tempted to make a direct causal link between the fertilizer in the pond and the dead fish.
Crosscutting Concepts
Cause and Effect [4] Students learn of the effects of a mysterious occurrence at Sunrise Farm Pond. In this experience, they will make initial predictions about the causes. They will revisit these predictions at later points in the pathway to see how their thinking changes as they learn more about the pond ecosystem.
Systems and System Models [5] The mystery itself is set at Sunrise Farm Pond, and the drawing template sets boundaries on the system that students are investigating. Although they will engage in experiences outside of this context to learn about producers, decomposition, and ecosystem dynamics more broadly, they will apply these concepts back to the pond and relationships under investigation.
Implementation Tips
- Note that the remainder of the pathway provides students with a rationale and supporting evidence to counter the idea that the fertilizer causes fish death directly.
- Give students time to discuss the scenario and the big question in groups. Then hold a whole-class discussion. The goal is for students to understand this basic version of the scenario but NOT to add other details from the full scenario (e.g., increased algae growth, decomposer use of dissolved oxygen) because we don’t want to give away these clues for solving the mystery at this point.
- Encourage students to include text with their drawings.
- Collect and keep the drawings, or ask students to keep the drawings, so they will be able to compare their thinking at various points along this pathway. A sample pond drawing [6] for this stage of the pathway is available. This sample is for your reference and is not intended to be shared with students. Of course, student models may not include all of the elements in the sample. Elements to look for and teacher guidance for instructional next steps are outlined in the rubric for student models [7].
Science Practices
Developing and Using Models [8] In this experience, students are introduced to the drawing template that they will use to explain what they think is happening in Sunrise Farm Pond, providing an opportunity to discuss the utility of modeling in science. It is important to help students make the transition from “drawing” to “model.” Acknowledge that they have been referring to their work as “drawings,” but that another name for what they have drawn is a “model,” and that students should refer to them as their “model” for the remainder of the pathway. Have students consider the limitations and affordances of their model as a representation. Students’ initial models will serve as a representation of what they understand so far about the situation at Sunrise Farm Pond. As their models increase in complexity over time, they will become tools that students can use to construct an explanation of the cause-and-effect relationships present in the pond.
Asking Questions [9] In addition to providing students an opportunity to ask clarifying questions about the story, provide students with time to generate questions about aspects of the pond they think would be important to investigate, prior to posing the suggested questions above. One approach is to have students write down each of their questions on a sticky note, and then as a class, organize the questions based on their focus. When student experiences later in the pathway address these questions, revisit the collection of questions as a class, encouraging students to identify which questions they are now able to answer. For example, students may ask, “What does the fertilizer do to the pond water?” and after engaging in Student Experience 3, they will have evidence to support the idea that fertilizer entering the pond causes accelerated algae growth.