Vernal pool food web and microscopy

One of my goals for this trimester is to make sure that students know that organisms need energy to live and grow, and that there are different trophic levels in an ecosystem. Since our project is about vernal pools (VP), I had kids create vernal pool food webs. I started by asking them how energy enters this ecosystem. After agreeing that algae and plants are the primary producers in vernal pools, I showed the kids pictures and short videos of other organisms that inhabit these temporary pools. This was necessary since this ecosystem is new to them, and they were not familiar with the species commonly found in vernal pools.

Once we were done looking at VP's organisms, we classified them as herbivores, carnivores, or decomposers. We spent some time discussing how energy moves through a system with all these trophic levels, and then created (as a group) a vernal pool food web. Working as a group in this activity wasn't a good idea. Some kids got really distracted and there were a few conflicts. After the break, we had a writer's workshop with Lorie. Sammy shared his idea for our vernal pool book, and everybody had a chance to make suggestions.

Last week some of the vernal pool cysts hatched - It was so exciting to see fairy shrimp, copepods, seed shrimp and tadpole shrimp swimming in the pools! On Friday, I brought a small microscope that connects to the projector so that we could take a closer look at these crustaceans. After having some fun with this simple microscope, I had a microscope station (with a compound microscope) for the kids to take a closer look at some of the microorganisms that are living in their pools. While one of the kids was with me at the microscope station, the other kids were working on two assignments with Brittany: 1) making their own vernal pool food web - it was important to give them the chance to do this activity on their own since not everybody had a chance to think about each relationship on the previous week; 2) start their field guide flashcards for some of the plants that we might see during our field trips to Jepson prairie.

The kids were really excited to use a compound microscope. I had each kid get a sample of water from one of their experimental pools, and prepare a slide for observation. Before letting them look at their slides, I talked to them about how a microscope works. We were able to see a lot of algae, and some rotifers.

Getting started!

          Two weeks ago we started the in-class vernal pool experiment. We had enough vernal pool soil (thanks to Jamie Kneitel) to  simulate 6 mini vernal pools. My goal was to let the kids choose two treatment groups so we could have 3 replicates of each treatment. Before letting the kids choose the treatments for their experiment, I talked to them about the importance of replication in scientific studies. I started by describing a simplified version of my husband's experiment - he is studying the effects of tadpoles (Pseudacris regilla) on vernal pool communities, and I asked them to think about a few possible reasons why a scientist would want/need to compare pools with tadpoles with pools without tadpoles. The reasons for having controls in scientific experiments seemed to be pretty clear to most kids. I then proceeded by asking them why we would want/need more than one pool with each treatment. The reasons for having replication in a scientific study weren't that obvious to the kids, so we spent some time talking about the importance of replication.

         After this discussion, I told the kids that our only independent variable in this experiment would be the amount of water, and I let them choose two treatments. Group 1 chose to simulate a heavy rain event, and filled up their 3 containers; while group two decided to simulate lighter, more frequent rain events - they have been adding a cup of water three times a weeks. Below are some pictures of the kids setting up their microcosms.

After we were done setting up the experiment, Lorie came into the classroom to talk to the kids about writing a book. As I have mentioned in my first post, we will be working on a children's book about vernal pools during the 3 months that I am working with the third and fourth graders. Lorie had a discussion with the kids about possible roles that they could have during this process. Although the kids will be working together on this project, we have some kids focusing on different roles: story telling, illustration, fun facts, scientific facts, and editing.

Last Friday, the kids started working on their field guides to Jeposon prairie vernal pools. My goal is to have each kid create their own field guide before we have our field trip to Jepson prairie so that they can use their own work to identify some of the species during their visits to the vernal pools. The kids worked on crustaceans ( clam shrimp, copepods, fairy shrimp, seed shrimp, tadpole shrimp, and water flea), and amphibians ( Pacific chorus frog, and California tiger salamander) last week. They did an excellent job drawing the species and summarizing fun facts about them.