Implementation of radioactivity in primary school physics lessons

This paper presents the results of the study on the knowledge of radioactivity among primary school students. For the purpose of the study, a teaching unit on radioactivity was designed. Data were collected using online instruments: knowledge test and questionnaire. 70 primary school students were included in the study and the pre-post design was used. The results show an improvement in knowledge about radioactivity after a teaching unit on radioactivity and no change in views about the use of nuclear energy.


Introduction
Students in primary school in Slovenia take physics classes at the age of 13 and 14 (8 th and 9 th grade) [1].Unfortunately, physics teachers often feel that physics is not a popular school subject.This feeling is supported by a research showing that physics is one of the least popular school subjects [2,3].There are no significant differences between attitudes toward physics and motivation to learn physics [4].This suggests that students are motivated to learn physics, at least internally, less.As teachers, we strive to bring physics closer to students by presenting them with as much interesting and current content as possible while staying within the curriculum framework of the subject.Examples of this can be found in the dissertations on the implementation of contemporary physics in physics education [5], in the articles in the Slovenian journal Fizika v šoli (eng.Physics in School) [6,7], etc.Therefore, we wanted to introduce students to the science topic of radioactivity, which is interesting to students and is not usually covered in primary school physics [8], although the possibilities for implementation within curricular topic Physics and the environment are evident [1].Various definitions of radioactivity can be found online.The Slovenian Nuclear Safety Administration [9] defines it as a phenomenon in which the nuclei of unstable atoms change to a stable state and emit energy in the form of ionizing radiation.
In our society, nuclear energy is occasionally discussed, especially in connection to the risks associated with its use.Discussions arise during various events that could affect a nuclear power plant, e.g.accident at the Fukushima-Daiichi nuclear power plant in 2011, anniversaries of the Chernobyl accident in 1986, earthquake near the Krško nuclear power plant in Slovenia in 2020, discussions about the second unit of the Krško nuclear power plant in 2021 and 2022... Nuclear accidents and the effects of ionizing radiation on living beings and inanimate nature are topics of great interest for students [10].
Radioactivity is not only interesting, but also contemporary topic.Lijnse et al. [11] have shown that students obtain most of their knowledge about radioactivity from the mass media, where the information is often insufficient or even wrong.Cardoso et al. [12] studied the misconceptions that Brazilian students have about nuclear physics.They included 34 students in the study and found that 60% had already heard about radiation but could not explain what it is.They also noted the influence of information that students had received outside of formal education, mainly through mentions of nuclear fission in the media (the subject of nuclear physics is not required in the Brazilian secondary school physics curriculum).In addition, we were encouraged to the study of Millar [13], who conducted a study with 144 students (aged 16 years).His findings showed that the students involved in the research could not distinguish between irradiation (the sample is exposed to ionizing radiation only, it does not radiate later) and contamination (the sample is infected and radiates ionizing radiation later).The same conclusion was reached by Siersma et al. [14], who reviewed the literature and interviewed 12 students.This led to the design of our study and the tendency to present some facts about radioactivity to the 8 th and 9 th grade students (students participating in physics classes) to introduce them to the topic.Specifically, in our study, we wanted to determine students' knowledge about radioactivity and students' views toward the use of nuclear energy before and after the implementation of the learning unit.The following research questions were set: How much knowledge will the students acquire after the implementation of the teaching unit?Will the implementation of the unit influence the students' views on the use of nuclear energy?

Radioactive decay
The basics of radioactive decay are explained below to facilitate understanding of the content of this article.In 1897, Henri Becquerel was researching the newly discovered X-rays.He accidentally discovered that uranium salts, when irradiated with X-rays, emitted a penetrating radiation that could be detected on a photographic plate.Further research showed that this penetrating radiation were not Xrays.Becquerel thus discovered a new phenomenon, radioactivity, for which he was awarded the Nobel Prize in Physics in 1903 [15].Radioactive decay is a natural process.An atom with an unstable nucleus will spontaneously decay -changing from unstable to stable and releasing energy in the process.The radioactive decay of unstable nuclei is stochastic process, meaning that decay of unstable nuclei, at the level of single nucleus, is completely statistically unrelated.The number of radioactive nuclei decays (dN) in a unit of time (dt) is a measure of the activity of the source.The activity (A) is defined as: The unit for activity is becquerel (Bq), which means one decay per second [16,17].
A nucleus can be deexcitated by three kinds of decay.These decays are alpha, beta (beta-minus decay, beta-plus decay, electron capture) and gamma.The active alpha nucleus dissipates its internal energy by emitting a helion, which is a particle with two protons and two neutrons.This releases some energy, which is carried away by the emitted helion in the form of kinetic energy.Since the active alpha nucleus loses two protons and two neutrons during alpha decay, its mass number decreases by four and its atomic number decreases by two.During the decay, an alpha particle (α) is produced The emitted helions sooner or later capture two free electrons from the atmosphere and helium atoms are formed, so helium occurs near alpha-active isotopes [16,17].
Beta-active nuclei emit electrons.When the beta-minus (β -) decays occur, the neutron (n) is converted into a proton (p), a particle β -(i.e., an electron), and an antineutrino ( �): In beta-plus decay (β + ), the proton is transformed into a neutron, a β + particle (i.e. a positron) and a neutrino (ν): In both decays, the mass number is retained.In the case of β -decay, the atomic number increases by one and in the case of β + decay, the atomic number decreases by one [16,17].
In gamma emission, excited nuclei are deexcitated (they release excess internal energy) without changing their composition.The nuclei emit gamma (γ) photons: The energy of photons emitted in gamma decay can be very high (from a few tenths to several MeV).Gamma radiation is an electromagnetic wave with very short wavelengths and is the most penetrating radiation.It is ionizing radiation because it ionizes atoms and thus can damage our genetic material.Alpha and beta radiation are also ionizing.Alpha radiation has a lot of energy and would pose a great danger to us if we ingested it, but fortunately it has a short range.It is already stopped by a human skin.Beta radiation, on the other hand, is more penetrating than alpha radiation but has less energy [16,17].
The mentioned basics of radioactive decay were included in the planned teaching unit on radioactivity, which was implemented in primary school physics classes.It must be mentioned that nuclear fission is not the same process as the spontaneous radioactive decay described above.Nuclear fission is an activated and controlled process in which the nucleus becomes highly unstable due to the capture of a neutron, which quickly leads to the split and thus the release of energy.

Methodology
We introduced the topic of radioactivity to primary school students in the school year 2020/2021 and assessed students' knowledge progress and their change of views.To conduct the study, we used the causal-non-experimental method of educational research [18].

Sample
The sample of the research included 70 students from two classes of the 8 th grade and three classes of the 9 th grade of a primary school near Celje, Slovenia.The sample was random, and participation was voluntary.
Instruments Data were collected using two instruments: a knowledge test to determine knowledge gain on radioactivity and a questionnaire to determine views towards the use of nuclear energy.The test and the The teaching unit used an excerpt from the Chernobyl series [19] to increase situational interest.We introduced the decay of nuclei (Figure 1), said that ionizing radiation is released in the process, and explained how we gain energy through a controlled chain reaction -so called nuclear fission (Figure 2).We also addressed the fusion of nuclei and discussed the arguments for and against the use of nuclear energy (Figure 3).In the discussion, we also referred to the Slovenian nuclear power plant Krško, which is accessible for student field trips [20].In designing the teaching unit, we relied on various sources [16,17,21,22].

Arguments for and against the use of nuclear energy
After the teaching unit on radioactivity, the students again filled in the questionnaire and solved the knowledge test.The questions of the knowledge test and the questionnaire are summarized in Table 1.A heavy lead shield (c).

The door (b).
A sheet of paper (a).

Q11
Which statement is true about a nuclear reactor?

A controlled chain reaction takes place in it (a).
An uncontrolled nuclear reaction takes place in it.

Q12
What are fusion and fission?Fusion means the collision of nuclei, fission means the repulsion of nuclei.Fusion is the process of movement of nuclei, fission is the process of meeting of nuclei.

Fusion is the merger of nuclei, fission is the split of nucleus.
Fusion is the process of acceleration of nuclei, fission is the process of deceleration of nuclei.

Q13
Plasma  2 and 3. To compare the knowledge of all students on a particular question before and after the lesson, we calculated the g-factor, where N is number of students who gave answers.The g-factor is given as: Progress in terms of g-factor is defined within the following benchmarks: g < 0.3 -low knowledge gain, 0.3 ≤ g < 0.7 -intermediate knowledge gain, 0.7 ≤ g -high knowledge gain [23].

Results
Table 2 shows the percentage of students who answered the questions correctly before and after completing the unit.It is obvious that students answered all the questions better after conducting the teaching unit than before, except for question number 6, and the average g-factor indicates that students showed an intermediate knowledge gain.However, the reason for the lower achievements on question number 6 after the introduction of the lessons could be that we did not emphasize this too much in the lessons, but at the same time, there is also the possibility of guessing, since the optional task type was chosen, which is a limitation of the knowledge test.
Table 3 shows that students' views toward the use of nuclear energy did not change.We assume that the topic should be discussed in depth for a longer period of time to change the students' views, as pointed out also by Ajzen and Fishbein [24].From the student observations, the students' reactions to the lesson were positive.They were happy to participate in the lesson.They said that the topic was interesting to them and that they would like to see more content of this type with more stories and less equations and calculations.A similar research was carried out by Pavlin [25], who wanted to implement contemporary science into physics education.She did this using the example of liquid crystals, which are found in the phone screens, computers, and also in many organisms [26].The research was conducted with high school and university students.The results show that students made an intermediate knowledge gain based on the g-factor (g = 0.56).Students were also in favour of introducing liquid crystal content into regular physics classes [25].The results of our study suggest something similar, but we did not systematically examine preference for contemporary physics content (radioactivity) at this stage.

Conclusion
Our paper shows that by implementing the unit on radioactivity in primary school physics classes, we can increase the level of knowledge of primary school students on this topic.The students' knowledge gain proved to be intermediate (the average g-factor was 0.42).We did not find any changes in students' views toward the use of nuclear energy.The results suggest that it is worthwhile to address the topic of radioactivity in primary school and to give teachers an idea how to implement this topic in the classroom.The above is consistent with the results of a recent survey of the 8 th and 9 th grade primary school students [8].Among the seven topics on contemporary physics, students chose radioactivity as the most interesting.Most students want to include contemporary physics content in physics classes.Moreover, students liked the lessons on radioactivity, and it had a positive effect on their knowledge and interest in physics classes.
As limitations of our research, we point out the limited scope of the study.A more extensive and longer study would lead to more in-depth conclusions.In most cases, the instruments we used had prepopulated responses, so that we could not obtain detailed responses from students, but we chose to use such instruments to facilitate data processing.The survey itself was conducted toward the end of the school year, when interest in school work was waning among students, at least some of them.
Since many politicians give at least basic approval to the construction of the second unit of the Krško nuclear power plant, at least in principle, our society will not be able to avoid discussions on this topic in the coming years, so it seems reasonable to include such topics in primary school physics classes because participation in such discussions makes sense only if the participants have at least basic knowledge on this topic.It is certainly necessary to study the topic on radioactivity in depth over a longer period of time in order to consolidate the knowledge.In further research, it would be useful to implement more extensive and complete teaching modules with many examples and problem situations and then evaluate their contribution in terms of knowledge, views (attitudes) change, reasoning, further research on the topic (e.g., self-initiated reading of popular science literature), etc.We believe that our research has raised a few new questions that scholars need to answer.

3rd
World Conference on Physics Education Journal of Physics: Conference Series 2727 (2024) 012003 IOP Publishing doi:10.1088/1742-6596/2727/1/0120034 questionnaire were created in online tool 1KA.Students accessed them via their cell phones.The knowledge test included 12 multiple choice questions.They were prepared for the purpose of the survey.The survey questionnaire contained one item on a five-point Likert scale with the required rationale.The procedure of the survey Students completed the questionnaire and solved the knowledge test before conducting the teaching unit on radioactivity in physics class.Next time we conducted a teaching unit on radioactivity.

Fig.
Fig. 3 Arguments for and against the use of nuclear energy

Table 1 Questions
with possible answers (correct answers are marked in bold) Number Question Possible answers Q1 What do you think of when you hear the word radioactivity?
Data processingData were collected in the 1KA online tool and transferred to Excel, where they were processed at the descriptive statistics level.70 students validly answered the questionnaire and the knowledge test before the lesson on radioactivity and 66 students after the lesson.The actual percentage of correct answers before and after the lesson and the views of the students towards the use of nuclear energy are presented 7in Table

Table 2
Percentage of correct answers of students before and after conducting the teaching unit on radioactivity and calculated g-factors according to the questions of the knowledge test.