I met students in the outdoor classroom for our first science lesson. I explained that science is everywhere, and that today we were going to see if we could find science happening right in our school garden. I reminded them that when we think like scientists, we look closely. So, first we are going to make observations of the garden from a distance. Then we are going to see what we can discover when we look closely.
From afar students could see sunflowers bending and drooping. We used our bodies to show how the sunflowers were bending and drooping. Then I passed out magnifying glasses to each student, and let the exploration begin. When students looked closely, they discovered seeds inside the flower heads and a whole community of organisms. They discovered ants, bees, wasps, slugs, and a ton of ladybugs at all different stages of their life cycle (egg, larva, pupa, adult).
Students recorded their observations and discoveries in science journals. On one side of the paper they recorded what they could observe from far away, and on the other side what they discovered when they looked closely. They were amazed at how many things they could discover when they looked closely!
Back in the classroom, we did some research to find out which insects are good for our garden, and which insects are bad. We discovered that ladybugs are really good for our garden. (They eat the bad bugs.) And, we discovered that aphids (the "stuff" under the leaves) are really bad for our garden. They suck plant sap, turning leaves yellow and killing the plant. Why are there so many aphids in our garden? Can the ladybugs rescue our sunflowers?
To further investigate the aphid population in our garden, we played a game of tag. Students (acting as aphids) went looking for habitat components (other students pretending to be food, water, or shelter). If the aphids found the resource they were looking for, they tagged it and the resource became an aphid. If the aphids did not find the resource they were looking for, they died and became part of the habitat. After each round of tag we collected data, recording the number of aphids in the population. The following week, we graphed the results.
We noticed that when resources were plentiful, the size of the aphid population went up. When resources were scarce, the size of the aphid population went down. Mid-way into the game, we added a ladybug predator. (See the arrow at the top of our graph.) With the advent of the ladybug, the aphid population size began to decline and eventually stabilized. Maybe there is hope for our sunflowers!
Now that we knew something about aphids and ladybugs, we were curious about what all the other creatures were doing in our garden. How do all these creatures interact to form an ecosystem? It turns out ladybugs are not the only ones that depend on aphids. Ants depend on aphids too. Except that ants don't eat aphids, they milk them for "honeydew" (i.e., eat aphid poop). In return for the honeydew, ants protect the aphids. Ants will attack any ladybug that tries to eat an aphid.
We decided to make a classroom model of our garden ecosystem using yarn, and we saw how everything is connected. The sun gives energy to the sunflower, the bees depend on the sunflower for nectar and pollen, the aphids eat plant sap, the ladybugs and wasps eat aphids, and the ants farm the aphids for honeydew.
We had our classroom ladybug tug on her string to see how many creatures might be affected by her loss. Then she let go of her string. What happened? When the ladybug in our classroom food web disappeared, it impacted every other organism in our ecosystem. Our food web eventually collapsed. This is a big problem! We needed to think like scientists! (Because scientists solve problems.)
After doing some research, I found out that scientists at Cornell University in New York are working to solve this problem. And they need our help! They have asked us to look for ladybugs and photograph them (especially if we find the rare nine-spotted North American ladybug). We can submit our ladybug photos to an online database to contribute to the study. Students were eager to participate in this citizen science project. (See the Lost Ladybug Project or Lost Ladybug App to learn how you can help too.)
When we returned to the school garden this week to search for the lost ladybug, the children immediately noticed how much the sunflowers had changed. The leaves with aphids on the undersides had now turned yellow and mottled. It's amazing how much damage a tiny aphid can do! Every student hurried about the garden looking for ladybugs and counting their spots. Each one was hopeful that they would find a nine-spot.
We submitted the three photos below to the Lost Ladybug Project. Each photo depicts a different species of ladybug we found in our garden, Hippodamia convergens, Harmonia axyridis, and Coccinella septempunctata. (Photos and data we submitted to the Lost Ladybug Project can also be found on the contributors' page here.)
After the harvest, students worked together to create a mural of the sunflowers and ladybugs in our garden. We revealed the mural at our Fall Family Science Night. Students were excited to share what they had learned with their parents. That completes our science in the garden. But we will keep looking for the lost lady bug! I am so proud of our young citizen scientists!