Integrating Science, Technology, Engineering, and Math in STEM Lessons

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The Academy of Aerospace and Engineering at John Wallace Middle School is a STEM (science, technology, engineering, and math) program. This means that we strive to integrate those four subjects into every lesson. It is not always possible, but it is the goal. We met this goal this week in 8th grade science where students did a lab where they extracted the DNA from a strawberry, examined it with the naked eye, then with a microscope. The science started when we began the week with an interactive lecture and web quest about genetics and DNA. Then we did the lab as an inquiry activity where the students were told how to extract the DNA from a strawberry, but they were not told what to expect they could see. I polled the class before the lab on who thought they would be able to see DNA, and most students thought they would be able to. I emphasized that scientists are skeptical – they must be convinced by evidence. We did the lab, and the students saw some fibrous material using just their eyes (no microscopes) after the extraction process. The next day, we prepared microscope slides of the fibrous material, then the students saw the fibers in more detail. I asked if they had seen DNA, and about half thought they had. That’s when we did the math lesson. We looked up the width of a DNA molecule — it’s about two nanometers, hundreds of times too small to be seen with an optical microscope. We discussed the sizes of various microscopic objects and what power would be required to see them. Then we learned about the technology behind electron microscopes, and the students learned how scientists can use these instruments to see DNA and other molecular-sized objects. The students concluded that they had seen multiple strands of DNA wound like a rope in the fibers they observed, not individual DNA strands. Finally, we discussed the engineering challenges and opportunities of using nanotechnology. In the end, we covered S-T-E-M though out this week. Coincidentally, Ms. Garavel was introducing the use of microscopes and making microscope slides to the 7th graders. Here are photos from these lessons:

8th graders making naked eye observations of extracted strawberry DNA:

8th graders making microscope observations of extracted strawberry DNA, along with one image of the DNA:

7th graders using microscopes in inquiry lesson:

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