let us examine how chemistry teachers can use smartphones to facilitate their learning goals, using the example of the ideal gas law, which is found in the secondary and post-secondary chemistry curriculum.
21.3.1 Examining Ideal Gas Laws with PhET Simulations
The ideal gas model (iGM) is one of the fundamental abstract models in both chemistry and physics encountered by students in their secondary and later post-secondary chemistry and physics courses.38 it is used to construct the
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Molecular Kinetic Theory of Gases, as well as to explain phenomena such as heat and energy transfer, thermal insulation, various thermodynamic pro- cesses, the relationships between temperature, volume and pressure of gas- ses, and finally, the laws of thermodynamics. iGM is one of the first models where students have to analyze an enormous number of miniscule invisi- ble objects on both microscopic (or even sub-microscopic) and macroscopic levels. Understanding this model helps students differentiate between fun- damentally different science concepts as heat and temperature, energy and work, thus building a foundation for studying thermodynamics.39
Consequently, iGM poses a number of conceptual challenges to the learn- ers. in addition to being often invisible, even a small volume of gas, such as air, contains an extremely large number of particles, thus making the analy- sis of their behaviour appear more complex. For example, one breath of air at standard pressure and temperature will contain about 1022 molecules.
Students, as well as many science teachers, do not have much experience with numbers of this large order of magnitude.19 Furthermore, iGM makes important assumptions about the behavior of the gas particles located in a closed container. (1) They have to be point particles, i.e., with no inter- nal degrees of freedom, such as vibrations or rotations. (2) The collisions between the particles are elastic, so the particles do not lose energy as a result of these collisions. (3) The total volume of the particles is much smaller than the volume of the gas container. (4) There are no long-range intermolecular forces between the particles or between the particles and the container walls.
Thus, iGM is a microscopic model that allows us to predict the behaviour of an extremely large number of gas particles that obey these assumptions. For its understanding, iGM also requires some prior knowledge (i.e., momentum and energy conservation laws) as well as the ability to visualize a complex system.39 Therefore, it is not surprising that many secondary students lack a deep understanding of this model and face difficulties applying it to describe properties of gases and the relationships between them.40
The microscopic iGM also helps explain the macroscopic properties of gases, such as their pressure, temperature and volume and the relationships between them, described by the ideal gas law:
PV = NkBT (21.1)
where P is pressure, V is volume, N is the number of gas particles, kB is the Boltzmann’s constant, and T is temperature.
To gain a meaningful understanding, students not only have to be able to make sense of iGM, but also to bridge the microscopic and macroscopic models. This will allow to describe each one of these macroscopic gas prop- erties using the microscopic iGM. For example, gas pressure can be defined as the average force gas particles exert on the unit area of a rectangular con- tainer’s wall as a result of the collisions with it:
ave 2
3
F mv
P N
A Al
(21.2)
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273 Smartphone Applications as a Catalyst for Active Learning in Chemistry
where Fave is the average force exerted on the area A of the container’s wall, l is the length of the container, m is the mass of an individual ideal gas par- ticle and v2 is the mean square of the particle’s speed (p. 595).38 however, as in the previous case, the mathematical concepts involved here might exceed secondary students’ knowledge. This is the place, where a teacher might introduce phET suite of computer simulations that the students can freely install on their smartphones, or other electronic devices (see Figures 21.3 and 21.4).
Correia and her collaborators33 have studied the effects of using phET sim- ulations on secondary students’ learning of the ideal gas-related concepts.
Specifically, they examined secondary students’ comprehension of the gas behaviour at the sub-microscopic level as a result of engaging with phET sim- ulations. Using the pre- and post-conceptual surveys, they found that student comprehension of the material significantly increased as a result. one of the reasons identified by the researchers was not only the opportunity to observe the behaviour of particles of an ideal gas, but the ability to change the vari- ables and observe the effect of this change on the system (see Figure 21.3).
The students were able not only to see the “invisible” particles, but to ask and answer the “what-if questions” through conducting relevant measurements.
For example, they could measure how the changes of the gas temperature affect its pressure. Even more importantly, the students were able to con- nect microscopic (the motion of individual particles) and the macroscopic (gas pressure, temperature) properties of the gas and their mathematical and physical representations. To address a common misconception—students’
Figure 21.4 a screenshot of phET interactive simulations Gas properties: Explore.
The simulation allows changing different parameters of the ideal gas system and observing and measuring the effects of these changes.
For example, students can measure the number of wall collisions and connect them to the gas pressure. reproduced from https://phet.colo- rado.edu/en/, under the terms of the CC BY 4.0 license https://creative- commons.org/licenses/by/4.0/.
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confusion between heat and temperature,40–42 they could use the energy part of this simulation (see Figure 21.5).
21.3.2 Examining the Ideal Gas Law with Phyphox
Complementary to examining iGM using phET virtual experiments, stu- dents can also collect and analyze data using the phyphox app (see Figure 21.6).36 as one example, consider an investigation of the dependence of the gas pressure on temperature in the ideal gas law. a student can place their smartphone in a sealed plastic container and measure how the pres- sure of the gas changes if the container undergoes heating. The latter can be
Figure 21.5 a screenshot of phET interactive simulations Gas properties: Energy.
The simulation uses multiple representations (e.g., energy and aver- age speed bar charts) to help students examine different properties of iGM. reproduced from https://phet.colorado.edu/en/, under the terms of the CC BY 4.0 license https://creativecommons.org/licenses/
by/4.0/.
Figure 21.6 Examples of exploring the ideal gas law with a smartphone. a smart- phone is measuring the air pressure in a sealed plastic container that undergoes heating (a) using a hairdryer and (b) by submerging the container in hot water.
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275 Smartphone Applications as a Catalyst for Active Learning in Chemistry
provided by exposing the sealed container to either hot air (e.g., from a hair dryer) as shown in Figure 21.6(a) or hot water, as illustrated in Figure 21.6(b).
Figure 21.7 demonstrates the result of such experiments. it shows the gas pressure gradually increasing with time as the air in the sealed container is warming up.
it is well known that smartphones cannot measure ambient tempera- ture in a reliable way, because of the constant and irregular dissipation of heat from its own inner parts. hence, a quantitative study would require a separate temperature sensor (e.g., a simple household thermometer) to be placed in the sealed container, which would provide an independent temperature read-out. With that data available, the linear dependence of pressure P on temperature T could also be examined by the students using eqn (21.1).
other examples of exploring the iGM include experiments on the depen- dence of the atmospheric pressure changes on altitude. here, students can take their smartphones to various places located at different known altitudes, such as different floors of a high-rise building or a mountainous terrain.
21.3.3 Science Teachers’ Motivations for Using Smartphones in the Classroom
There are many reasons why secondary science teachers might want to use smartphone-based technologies in their classrooms.26,43 These technolo- gies have already become parts of students’ lives and the students are very Figure 21.7 a screenshot of a computer remotely connected to the phyphox app measuring ambient pressure as a function of time with a smartphone in a sealed container. at t = 2 s, an external hair dryer was turned on to warm up the container, hence raising the temperature of the air inside it. reproduced from https://phyphox.org/, under the terms of the CC BY 4.0 license https://creativecommons.org/licenses/by/4.0/.
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comfortable using them. Thus, educators might create virtual science learn- ing environments using the devices already familiar to the students. how- ever, smartphones can also help teachers to level the educational inequality with regard to doing real science, where the science lab equipment in the school is rather limited. Engaging students in doing science is very different from asking students to read about science discoveries done by others. it also allows students to experience authentic process of scientific discovery from planning the experiment to implementing it and analyzing its results.
This claim was echoed by many British Columbia teachers whose students participate in annual hands-on physics olympics at the University of British Columbia.44,45 Therefore, modern smartphone-based technologies have the potential to reduce inequality in technology access in our schools, as many students in remote and rural communities already own this technology, while their schools might have limited science equipment. With the use of sensors already embedded in students’ smartphones, science educators can make another step towards meaningful student engagement: moving from virtual science learning environment towards doing science in an authentic real-world context.25 however, to make this important step, science teacher educators have to support science teachers, who might have never experi- enced these learning environments as students.