Permeability Part 3 - Permeability Studies in the Field
New York’s Urban Ecosystem Lessons
This is the third in a series of four lessons on the permeability of surfaces in a watershed. These lessons can be done together or individually. If you plan on doing all the lessons in the permeability series, then you should consider doing them in the order suggested: Part 1, 2, 3, and then 4. This series works particularly well after the Watersheds series of lessons. In this lesson, students will visit the location you have chosen and pour water on different outdoor surfaces to identify and quantify the real permeable and impermeable surfaces in the field. Then they compare the field observations to their earlier interpretations of satellite imagery of the same location. If you are not following the Permeability lesson series, you may wish to omit the satellite imagery portion of the “Evaluate” section of this lesson.
Understand that and how surfaces absorb water
Compare permeable and impermeable surfaces
- Draw conclusions about what types of surfaces do the best job absorbing water
Materials and Resources
SuppliesIn the classroom, a way for everyone to look at the same online Google Map at the same time. Projecting works best. This is also possible if everyone has their own screen and you provide very detailed instructions about what to look at when. A good color printer/copier might also be able to produce the satellite images you need, for distribution. In the classroom, a way for everyone to look at the students’ field predictions and data. Most likely you’ll have at least one night between the data collection in the field, and the discussion of that data in the classroom. So you can collect their work to compile the data and then hand it out.
Before you get started
Tips for Teachers
(optional but highly recommended!)
A day or two before your field visit, remind your students that they will create a model of the permeability of surfaces in that location, using the sponges and other materials they have been testing. Tell them that they will be visiting the location, in order to see for themselves what the surfaces are like -- not just from satellite imagery. And in fact, they will be testing the permeability of surfaces in the field.
In small groups, ask students to brainstorm ways of testing the permeability of the real surfaces in the field.
Ask them what materials they’d like to have available.
You might remind them of the kinds of measuring devices that the school can usually provide, and ask them if or how they might be able to use them to gather this kind of information. That list might include things like
Rulers, meter sticks, tape measures, string
Scales or balances
Graduated cylinders or similar devices for measuring volumes
Whatever else comes to mind and would be easy enough to bring to the field
Ask students to share ideas, take notes on those, and collect any written work you’ve assigned. Then it’s important to gather as many of the materials they’ve mentioned as you can, and bring them to the field visit!
Take students to the location you have chosen. This would work extremely well as part of a visit to the class’s ORS!
On the Observation/Inference chart, ask your students to:
observe and list and describe all the different surfaces they encounter (concrete, asphalt, tree pit, grass, mulch, etc.) in the “Observation” section
predict which surfaces are permeable and impermeable, and record predictions in the “Inferences/Predictions” section
If possible, encourage students to document the surfaces they are observing with photographs.
Now your students will test the permeability of the different surfaces. This is a fantastic opportunity to get students to design their own methods of testing! You might set particular parameters, such as: everyone has to collect at least 10 data points, and/or everyone needs quantitative data (data with a number, something you can count or measure), etc. If you need to be more directive, you could tell them how to do the testing, for example:
Choose one particular surface type to experiment on.
Using your water bottle, pour water on your chosen surface type.
Record results in the “Notes/Results” section of the Observation/Inference Chart.
Repeat steps 5-7 as many times as you have time for.
Compare how quickly the water is absorbed (if at all) on the different surfaces.
- If possible, encourage students to document their testing procedures with photographs.
At this point you may want to return to school, and complete the following in the relative quiet and predictability of the classroom.
Ask your students to compare the results of their field surface testing to:
The predictions they made while in the field -- could you always tell which surfaces were most permeable just by looking at them?
If not, why might water behave differently than expected? What new questions does that raise?
The Surface Types handout -- are your results consistent with what it says on the handout?
If not, how would you alter the handout to make it more accurate, based on your testing?
What they thought they were seeing on the satellite images from Part I of the Permeability lesson series -- what did you find easy to spot in satellite images, and what seems harder to gauge without going to the site and testing it for yourself?
Lead another class discussion about students’ field-based experimental designs.
Start by posting/distributing their data.
Start with open-ended questions like:
What do you notice about these data?
What questions do you have?
Are there any surprises? Any contradictions?
Encourage students to speak to one another, not just to you, and encourage them to follow up on each other’s comments and questions. For instance:
if Student A asks a question about Student B’s data, ask Student B if they’d like to try answering that question.
Then ask Student B’s partners if they’d like to add anything.
Then ask Student A if they are satisified with that answer, or if they have any follow-up questions.
Then ask Student B and group if they have any follow-up questions.
Of course, it’s possible to overdo this kind of prompting, but when it works, it can create powerful exchanges of ideas!
Ask a couple of groups to describe and demonstrate how they did their testing. Choose groups that used slightly or very different methods.
Then ask those groups and the rest of the class:
What are some of the similarities between these two experimental designs (or methods of testing)?
What are some of the differences?
What are some of the pros and cons of the different choices that each group made in their experimental design?
If you were to repeat this testing, what would you do the same as one of these groups, and what would you do differently? Why?
- Do you think each group tested permeability, absorbency, both, or neither? Why?