I begin this lesson by asking students to define a scientific model. I ask each group to come up with a definition and to record their definition on a sentence strip. I display each group'd proposed definitions in the front of the class.
I then show students examples of models (e.g. a model car, model of the solar system, model of the human heart) and ask why it might be helpful to use a model. As students share their answers I record them on the whiteboard.
I inform the students that they will be creating a model of a stream system in the class today and discuss why a stream model could be useful to our class as we study land and water.
To goal of this discussion is to have students understand that models allow us to conduct investigations which might otherwise be impractical or unsafe. Models also allow us to learn about a subject.
Before each student group can create their model, they will need to make a plan about how to best create a working model. I distribute a copy of the stream table set up document to each student. I ask the students to work together with their team to convert the amount of each soil type to be used in their model from the metric measurement to a customary measurement. I then ask each student group to determine which system of measurement will be most useful to them in creating their model. Allowing students to choose a system of measurement forces them to critically evaluate each system of measurement and to make a group decisions based on student-selected criteria.
I then ask each student group to detail why creating a model will be useful to their group. This serves as a quick assessment of student learning from the previous lesson section.
For the final portion of the lesson, students work together to construct their stream model. I group students into teams of four so that each student has the opportunity to add one soil component to their stream model. Students use the measurements from their planning sheet to add the correct amount of sand, gravel, clay, and humus to their stream table models.
A video of students completing this task can be found here.