Lesson Reflection
Models are used in science to represent a system. Models help us grasp the relationships between parts of a system or help us better understand a phenomenon. I have often used models to help my students understand the topics we read about. I feel one of the jobs of middle school science is to help students visualize the concepts of science so that when they can connect further learning to those ideas. Models help explain an idea and allow students to better grasp complex concepts. “Even better than knowing about powerful models is knowing and doing scientific modeling” (Kenyon, 2008, p. 41). To teach my students about the interior structure of the Earth, I had them create a 1 mm to 1 km scale model of the Earth’s interior layers. I know that students understood the relative thickness of the layers after completing this activity because of the way they evaluated the models I presented to them. Students also evaluated the effectiveness of using an egg to as a model of Earth’s interior layers. Journal entries reflected understanding of the differences and similarities between these two structures.
The most successful part of the lesson was the investigation of the egg and Earth’s interior structure. During this investigation, students were scanning their books for more details about each layer of Earth and identifying similarities and differences that were quite impressive. The journal entries that were created from this investigation showed me what students understood and what I needed to reteach. I focused on the misconceptions as we created the models of the Earth the next day.
I should have students create their models of Earth’s interior before doing the egg-Earth investigation. Because the egg-Earth investigation was such a powerful piece, I think making the model first would provide students with more information that could be used for their comparison of the two structures. This year I revisited the comparison and had students write a paragraph stating why they think an egg is a good or bad model for the interior structure of the Earth. I know students would have been able to identify even more similarities and differences between the two structures if they had more information about Earth’s layers before doing the investigation.
Creating a model helped students see the different layers as separate parts of a whole. Although we read about traveling through layers of different materials at the beginning of the lesson, I do not think that my students understood how different each layer was. After making their own model, figuring out what the layer was made of, and how thick it was, students were having discussions about the differences of each layer. The part of the lesson that most impacted my students with disabilities was a virtual field trip through their model. I had students point to the area of their model being travelled through as I reread “How to Dig a Hole to the Other Side of the World” (McNulty, 1979). Students were amazed at the fact that even though Earth’s crust is the thinnest layer, we have never drilled completely through it. We made several stops in Earth’s crust to talk about how deep humans have been, how deep the deepest mine is drilled, and where ground water is found. I was impressed by all the facts they remembered from the story and how they wanted to tie that information into their model.
The day after this lesson, to review and evaluate student learning, I showed students several models of the Earth’s interior and asked them to explain what was good and bad about the models. Students showed understanding of the increasing heat as you move from the surface to the core. They showed an understanding of the physical properties of each layer and every student was able to recognize if a layer was too thick or thin. They also shared other facts they had learned as a result of this investigation.