This standard emphasizes the need to uses multiple forms of assessment to demonstrate learning and engage learners in the process. Per this standard, assessment is not just a way to grade learner or monitor their progress, but is also a way to guide future lessons. To demonstrate this standard, I used two different assessment methods, formative and summative, to monitor understanding. The results from these assessments could also be used to inform future lessons in an actual teaching role.

The lesson I taught was on the history of the atomic model. Prior to the lesson I asked students questions to check their understanding and uncover any alternative conceptions to be addressed in the lesson. Below is an image drawn by one students during the interview followed by questions and their responses.

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This is the image referred to in the interview questions below. In this image, the learner drew diagrams learned in a lesson about properties of matter. They identified the small circles drawn as atoms.

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Interview Questions

Question: What do you know about atoms?

Response: Well, they are really small.

Question: How small?

Response: You need a microscope to see them.

Question: Do they have any parts?

Response: No. I don’t think so

Question: Are they part of anything?

Response: Yes. Everything. I know they’re everywhere. They make up matter and they join together for stuff.

Question: What kind of stuff?

Response: I don’t know, science stuff.

Question: What are you drawing?

Response: This is what I remember about atoms.

Question: Where are the atoms in your picture?

Response: *Student indicates atoms on the picture

Question: What do they look like?

Response: They are a ball.

Question: How do you know that?

Response: That’s what my science teacher drew.

 

The lesson addressed some these alternative conceptions directly. The first alternative conception is that atoms can be seen under a microscope. Scientists have used electron microscopes and tunneling microscopes to see the outline of atoms, but many microscopes they will encounter will not be able to show atoms. I was informed that for the purposes of the SOL test, the answer should be that atoms are too small to be seen with a microscope because they are asking about standard microscopes.

The next conception to be addressed was that they have no parts. This was addressed through the evolution of the model. Students realized that their idea was more related to the earlier Dalton model, but that the modern model includes protons, electrons, neutrons, and quarks.

The final conception was the drawing of molecules. This was indirectly addressed in the lesson by showing correct model of atoms. Unfortunately, this is one that may reoccur as this is how students draw atoms in matter, which may lead to students returning the idea that they are balls and not that that is just a simplified drawing. Below is an example from a unit plan that almost exactly matches the student drawing. 

In the chapter in Baker and Piburn (1997) one alternative conception was that atoms vary in shape. This is not one that arose in the interviews I conducted. All students who drew an atom drew it as a small circle and said they are like little balls. Another is that atoms and hard and heavy in solids, wet and runny in liquids, and light in gases. Unfortunately, this is not a preconception that I asked directly about. The one student who addressed states of matter did not mention weight but drew atoms as being packed more tightly or loosely depending on the state of matter. Last, they found that students believed the visible and physical properties of substances was present at the atomic level. Again, this is not a question I asked directly, therefore I am not sure what beliefs students have about this.

In another study done (Horton, 2007), they found three alternative conceptions about atoms. Two are about the physical property of atoms which was not addressed and the last was about the behavior of electrons which was addressed. The first two are that atoms are hard like billiard balls, and that atoms are soft and fuzzy. We did not talk about the physical property of atoms, so I am not sure what students’ ideas are about this. The third is that atoms have electrons circling them like planets around a star. This is like the conception mentioned earlier that electrons orbit the nucleus like planets around the sun. This was addressed by directly explaining the difference between the behavior of the electrons in the models as they evolved over time. The Bohr model may lead students to believe this, but I believe this is addressed further in the electron cloud model, where we explained that there are energy levels, but that electrons do not simply orbit in a direct path.

 

References

Baker, D. R., & Piburn, M. D. (1997). Constructing science in middle and secondary school classrooms. Boston: Allyn and Bacon.

Horton, C. (2007). Student alternative conceptions in chemistry. California Journal of Science Education, 7(2), 1-78.