The foggy tree is a metaphor for how nonscientists think about radiation. The whole topic is unclear to them, although they do have some ideas. (And, unfortunately, their ideas are not consistent with the scientific view).

You don’t need to be convinced of the importance of radiation literacy among the general public. The use of medical radioisotopes is rising, nuclear power is important in many countries, and the world was profoundly affected by the Fukushima disaster. People need to know what radioactivity is.

There was another crisis in Japan -citizens did not understand what radiation is and had few options to protect themselves or help others.When people suddenly are faced with radioactivity, they have questions.These are the questions a radiation literate person should be able to answer.

As a teacher, one needs to know where the students are coming from. For example, many people need some background knowledge on atoms before they can learn about radiation. Secondly, if people have difficulties with the topic, it really helps to know in advance.

This is my classroom. The students work in groups doing experiments and trying to understand the results. I do not tell them answers.This is also my research lab. We do lots of experiments - we ask questions about what is going on with the students, try things, and see what happens with the students. The next slides show some examples of what we have found:

We ask this question at the beginning of teaching about radiation. We get similar results every semester. Most students (including some of the 40% not counted here) think of radiation as being like some kind of material stuff.

The students are still thinking of radiation as stuff - if it gets on the strawberry, it will be radioactive. But there is another problem - students say radiation is radioactive.

Conflating radiation with radioactivity is very common. Actually, it’s just failing to distinguish between the two –students think it’s all one thing.

The naive view of radiation and radioactivity can be boiled down to some simple statements. Note that students are thinking of radiation as some type of material, rather than as a process. They have radiation in the wrong ontological category! (They are thinking of it as a noun when actually it is a verb –particles are in motion away from the source, so we SHOULD say “radiating”.)

The descriptions of the student difficulties have changed slightly over the years but please notice that the same general thing has been found in different countries in Europe and in different states in the US. This is a very common way of thinking about radiation!

We found this paper with an online search. Some of the findings are in the next slides. You may believe that the Pakistani education system is not as good as in the US – but on the other hand, we don’t have data on what US medical students think radiation is. I predict that when someone asks similar questions of US medical students, similar results are likely to be found.

The paper is not explicit about student answers and only lists the number of students who answered correctly. (In this case, the 39% who said no). I have assumed that the others said Yes, although some could have said “I’m not sure”.But the main point is – should we be satisfied with only 40% of medical students knowing that the x-ray machine DOESN’T make other things radioactive?

Suppose a similar finding were to hold in the US - Should we be satisfied with it?

Apparently the students in the Pakistani study did not distinguish between EM and ionizing radiation –which is the same as I find with my non-science majors.

“Being explosive” is just another of the “bad traits” of radiation/radioactivity.

These are results from a questionnaire we developed for our classroom. This are the pretest results. Note that nearly all the students come into the classroom thinking along the same lines of radiation being matter-like.

Actual student drawings. This is what they drew.Most likely, most students have been taught about where the components are in atoms, but they probably were NOT taught about why electrons remain held in place around the atom, or why there can be different numbers of neutrons in the nucleus. Most students do not have a useful or functional mental model of atoms.

These are the most common responses! And even if you accept “bonds” and “the nucleus” as valid explanations, these three add up to only 40% of my students’ responses.

These were two learning difficulties that I didn’t expect when I started teaching about radioactivity. But there are more!

Students will say that good radiation is used in chemotherapy to treat cancer, bad radiation causes mutations

The reason we laugh about this is that the learning difficulties feel overwhelming at times. But they must be dealt with!

The IiR materials are designed to deal with those learning difficulties.

The unit is divided into four “Cycles” –these are the topics addressed in each of the cycles. Note that we had to move all discussion of ionization and half lives to the very end of the unit because students couldn’t understand these topics any earlier.

Cycle 1 involves a lot of experiments with geiger counters and radioactive sources. We have to explicitly test EM sources vs. ionizing radiation sources. We have to explicitly check to see whether taping a radioactive source to an object makes it radioactive. And even after we do these things, students are still not convinced that radiation WON’T make other things radioactive. The students have to investigate atoms and ionization before they change their thinking.

Cycle 2 is about atoms which is a total non-sequitur for many students. (They don’t expect that atoms have anything to do with radiation)!We developed the Atom Builder (http://www.camse.org/sims/builder) to allow students to build and test any atom and any isotope up to element 115.

Students test their atoms and discover attraction and repulsion effects of ions. Some students initially expect ions to be radioactive. We need to extensively discuss the non-radiation effects of ions.

Once students are clear on the behavior of ions, we allow them to build and test radioactive atoms. It gets complicated! But students eventually figure out what is going on.We have to have a big discussion about whether the high speed particles exploding out of atoms might be radiation. The class eventually accepts this statement but it doesn’t affect a lot of students’ thinking until later.

Cycle 3 is about the interaction of radiation with matter, and how radiation can harm people and how it can be used in medicine.We want students to develop a viable mental model of how radiation interacts so we start with the “Atom Invaders” simulator and develop little causal stories about how a beta can push other electrons out of an atom, how an alpha can attract electrons out, and how a gamma simply gives its energy to an atom’s electron.

Students need more practice thinking about the interaction of radiation with everyday objects, so we use the Tracks simulator to incite discussions about how betas and alphas will interact with many atoms along their paths.

The tracks simulator enables views of the action at three size scales – macro scale, cell scale, and molecular scale. This is a beta traveling through a researcher’s hand, leaving behind a trail of damaged molecules. Itis not easy for students to work out what is going on in this situation but they eventually succeed.

Here is a view of a beta traveling through the hand, seen at molecular scale. Each of the pink/teal blobs is either a water molecule or an amino acid. The red glow is from a molecule that has lost an electron.

After working through the ionizing effects of radiation in Cycle 3, we investigated student thinking by examining their answers on homeworks and exams. Semester after semester, we find that roughly 65% to 80% of the students reliably are using the “particles in motion” view of radiation at this point.

In a separate study, we examined student understanding of ionizing by radiation and compared their “ionizing scores” to scores representing understanding of radiation as particles in motion. We found a strong correlation between the two, which suggests that students have to be thinking about radiation as particles before they can understand its ionizing behavior. This may be something you would expect but it’s nice to see that our

guesses are right!

Please feel free to use the simulators, download the course materials, or look through our research results. And feel free to contact me about teaching radiation and radioactivity!