I begin them two weeks into the semester to give students to become acquainted with the course and to gather supplies they'll need for the build. Over the years I've learned a few things that help the columns function better and ways to work error into the project, leading students through problems they can solve that are connected directly to the course.
This project is conducted all of first semester. I start the build in unit 1 and end in Unit 5. Usually we deconstruct our columns before winter break and then create the final poster when we return, since our semester ends in mid-January.
My students finish this project with a very strong understanding of:
- The nutrient cycles, especially nitrogen
- Concepts of eutrophication
- The relationship between cellular respiration and photosynthesis
- Soil properties and its relationship with the hydrologic cycle
- Water quality monitoring
I have modified my ecocolumn build from the work of Kristi Schertz at Teaching AP Science. Changes were made based on my probeware, newly released CED guidelines and experience predicting issues with the columns. As students experience issues, such as sedimentation in their aquatic columns, I use real time learning and teach them weathering, erosion, sedimentation and the effects of turbidity, for example.
This activity begins with the building and monitoring of the ecocolumn and runs from unit 1-4 of AP environmental science CED. During this time period, students complete journaling where they record data in a spreadsheet, make observations and reflect on the concepts the ecocolumn connects to. During this period, I'll collect their notebooks at times when I feel appropriate and read their entries. There is a lot of reading but I find it a valuable tool to see the depth of their learning. Their answers to the prompts help me identify areas I need to cover in more depth and shows me the connections they are making to the class standards. To reduce grading, you could collect one notebook per group and give a group grade.
Here are some tips on how to run this portion of the ecocolumn experiment:
- Give students time to gather supplies. In the instructions, they mention using flat bottom bottles. These are not readily available in my area so we use typical soda bottles. Encourage students to choose thick plastics with flatter bases. No green bottles. If they bring a green bottle, they should only use it for the filtration (middle section).
- My instructions use Vernier Probeware, LaMotte rapid test tabs and Rapitest soil testers. There are many different types of tests on the market. Use what makes sense for your budget and supplies on hand.
- For several years I used guppies in the aquatic chamber. Some years it was very successful but one year they all died. We all felt terrible. I made a switch, then, to aquatic snails. You can order them through Carolina Biological supply for very low cost. I keep an old aquarium in my room with duckweed, elodea and snails and its completely self sufficient with the exception of adding water now and again. I haven't needed to order any since that first year since they grow so well.
- I get basic pea gravel and topsoil for the terrestrial chambers. Avoid fertilized soil as it'll create eutrophic conditions in your aquatic chamber. It's interesting to see how the soil changes so much between groups based on their choices.
- Use "mistakes" or problems students encounter as a class learning opportunity. Many things will happen unexpectedly but they all fit in the curriculum!
- Provide students with many different seed choices. Some of the most interesting columns have a variety of grasses in them. There are always groups that have no sprouting that occurs and I'll suggest they use mung beans at that point. They sprout within 3 days in any soil and grow well.
At the end of the semester (Unit 5) we'll dismantle our ecocolumns and analyze them. This is a great opportunity to have students compare early soil structure to later soil structure and see the effects of erosion and plants on soil quality.
During this section of the project, we also look long term at the data. Showing students how to find patterns in data and to think about how those patterns occur is very important. At this portion of the project we discuss cause-effect and study major systems of change to see if our data fits those diagrams. We also talk about scientific error and the difference between causation and correlation.
The final portion is for each group to prepare a scientific poster and presentation. The posters are modified from University templates and students create them collectively. When they make them, I tell them to be sure to work on it while logged in on their google drives. That way, I can see the group history and know who made each section of the poster. They are also responsible for explaining their poster sections during the presentations.
To improve the quality of the posters, I always start with a group analysis of past posters. Students use the scoring guide for the project and grade posters from previous years. I give all groups two or three posters that look completely different. This activity improves the quality of their outcomes in several ways- first it shows them models so they understand what to expect. Second, by grading them, they can work with the scoring guide and know clearly what I'm looking for. Third, each poster is unique to the column and the changes that occur. Many groups will develop envy over another's outcome. By showing them how even a desolate ecocolumn has potential for an outstanding poster, they understand that all ecocolumns have their own personality and that they need to focus on what happened to theirs.
I test at the end, giving a 25 point comprehensive quiz. This is not shared here because I create it in AP classroom using AP exam questions that align to the topics in the ecocolumn.
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