A New Approach to Teaching Atomic Theory
Chemistry Teacher, Webster Schroeder High School
Ever since I started teaching chemistry, I would dread the mandatory 2 days I spent in my first-year chemistry course teaching the history of atomic theory. It was dry and tedious and boring for everyone involved. Dalton, Thomson, and Rutherford are important, but a bit of a snooze fest.
This year, I used the activities in Carolina’s Reconstructing Atomic Theory kit from the Inquiries in Science® series. This activity goes through the work and importance of Dalton, Thomson, and Rutherford, but does so using demos and lab experiences. I noticed a drastic increase in student engagement compared to traditional lecture on the history of atomic theory.
Why? Because by using this activity, students don’t learn about Dalton, Thomson, and Rutherford by simply writing down what they did. By performing simplistic experiments that mimic that work, students better understand the conclusions that were drawn about atomic theory—all while doing hands-on and minds-on work.
And after all, don’t we want to teach science history by having students do science? That’s the beauty of this module.
Setting the stage
The class is divided into 3 groups of equal size. In each of these large groups (which I call A, B, and C), the students are further subdivided into Dalton, Thomson, and Rutherford groups. Each smaller group takes ownership of learning about a scientist, and then they report their findings back to the large group in a jigsaw format.
In forming these groups, the module suggests putting students with the highest ability in the Dalton groups, as they’ll be taking the most measurements and using fine motor skills. The module also suggests putting lower-ability or more kinesthetic learners in the Rutherford groups.
I followed these instructions, and it worked out perfectly. My higher-ability students needed virtually no intervention in their experimental designs for the Dalton work, and my more rowdy students loved the idea of playing a game by simulating Rutherford’s gold foil experiment.
Part I: Investigating an individual scientist
Students are shown to “stations” for the scientist they have been assigned where there are further instructions. At the Dalton and Thomson stations, students must first follow a lab procedure and record data. At the Rutherford station, students use a game to simulate Rutherford’s experiments, and they collect and analyze data.
After students have completed their experiments, they then receive further information about Dalton, Thomson, and Rutherford. They read this and answer questions, thereby learning more details about the work of the scientists.
At this point, I include the demos and videos that I normally do for atomic theory, but I only show them to the individual scientist’s group. That is, I don’t show all my students the cathode ray tube demo, just those students who were part of the Thomson group. Only my Rutherford students watch the YouTube videos describing the gold foil experiment.
The module suggests having the students complete the reading about each scientist as homework, and I recommend this idea. Different groups work at different speeds in the experimental phase, and this is a way of getting all groups back on the same page. If students finish their experiments early, they can work on the reading in class, but if their experiments take more time, they can answer the questions as homework.
Part II: Dalton, Thomson, and Rutherford, together again
Once the students have completed the work for their assigned scientist, they then head back to their original group of A, B, or C, and share their findings. My students use white boards to show and explain the data they collect in their initial experimentation. Next, they take turns summing up the main points from the readings. Some of the students replicate the demos I had shown them so the rest of their group can see, or they describe what they watched in the videos.
After each scientist group shares out, the groups then pool their information and construct a timeline on a piece of poster paper that includes pertinent dates, descriptions of work, and a picture drawing of what each scientist thought the atom looked like.
Part III: Defending their ideas to Aristotle
Each group presents their timeline to the class. I play the role of Aristotle, and I question each group as to why they could say the atom looked the way it did. For each advancement of the model of the atom, students describe the experiments that led to it in order to defend the model.
I’m never lecturing on Dalton, Thomson, and Rutherford again. Instead, I intend to use this module to have my students learn about the development of atomic theory by actually doing science instead of just writing down notes on important dates. My students are engaged and involved, and it allows for differentiation in a heterogeneous classroom. Students must conduct their own investigations, demonstrate their understanding of ideas, and defend their work. It’s a breath of fresh air into what has, historically (pun intended), been a dry-as-dust topic.