Sensors and Measurements

Teaching Modul from Poland

Most research work involves observation, analysis, and interpretation of results. When planning to get students interested in scientific research, it is worth supplementing their activities with these components as an essential part of the experimentator's work. Due to the limited equipment conditions of schools and the pandemic necessity of conducting experiments at remote locations, often without the possibility to use specialized equipment, we suggest using materials and tools available in the household.

The activity scenarios proposed in the H0 section ("Measurement Errors") deal with the simplest of measurements, allowing students to understand that obtaining different results is normal in the world of measurement. For example, as a class we can measure the diagonal of an A4 sheet of paper using a variety of school rulers, tape measures and carpenter’s tape measures to find out about gross, systematic and random errors. Students can also note the differences in accuracy classes of instruments used and indicate their use in class-appropriate measurements and suggest ways to obtain more accurate results. It is also valuable to discuss and answer the question of the "true" length of the diagonal of a measured sheet of paper.

The quantities obtained as a result of direct measurements are often included in further calculations by applying formulas. The considerations involved in such activities can be examined using the example of building a pendulum proposed in section H0 and determining the value of the acceleration of gravity with it. In this case the students, using a thread, a weight and a stopwatch, have the chance not only to investigate the influence of individual variables (e.g. length of the thread, period of oscillation) on the result and possible accumulation of errors, but also to notice the influence of the human factor and the value obtained by automatic measurements, which will be part of subsequent scenarios.

The main theme of the scenario activities proposed in section H1 ("In Motion") is the potential energy of elasticity represented by the example of a stretched rubber band. Both the introductory experiment to investigate the distance of the bottle cap launch as a function of the rubber band tension deflection and the final vehicle race challenge address the same issue. Getting students interested in the transformation of potential energy to kinetic energy and understanding the relationship defined by, for example, Hook's Law can be made easier just by using elements from the environment rather than a specialized physics lab.

Scenario H1 involves the construction of a vehicle in which the role of propulsion is played by a stretched, twisted rubber band. Pupils can freely determine the method of transmission to the wheels and propose their own construction, but for the purpose of standardization of the challenge we have developed a model based on 3D printing. Students will receive printed components ready to assemble or they will print their vehicles themselves using the files provided to them (perhaps making interesting modifications), developing digital competence

It is of course possible to organize competition between individual teams and constructions based on standard challenges, e.g. maximization of the distance travelled by the vehicle. But to broaden the construction and IT competences of the students, we suggest to extend the elements of the competition by using a smartphone with preloaded application such as Arduino Science Journal, which has the ability to record, for example, acceleration. The phone placed on the built vehicle (as a support platform) can record changes from the built-in accelerometer, which after appropriate mathematical transformations will allow to determine the speed of the vehicle; This can be adopted is the proposed challenge "who is faster".

In the following sections we offer teachers the possibility to choose the measurement tools which they will use in the experiments, based on to the level of familiarity with programming (exhibited by their class as well as by themselves) so that they can feel confident with the implementation. The experiments described in the scenarios can be carried out using either a smartphone or a dedicated sensor operated by a microcontroller.

The focus of section H2 ("Pendulum") is the motion of a pendulum. The experiment consists in measuring the period of oscillation of a mathematical pendulum, which will be built by students themselves. Measurements will be done using built-in sensors in a cell phone and a special application, or in a more advanced way, which consists in building a measuring device based on a light sensor and a microcontroller. The course will cover topics such as harmonic motion, acceleration, vibration theory, and data analysis.

In section H3 ("Electromagnetism") students will construct a simple model of an electromagnet. With the help of an application in a phone or a self-made sensor (based on the Hall’s effect), experiments will be carried out in order to determine the dependence of the intensity of the electromagnetic field on the parameters of the electromagnet (e.g. the material of the core or the number of coils). On the basis of their observations and conclusions, the participants will build a simple device for sorting coins.

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