Task 2

It is suitable to realize this task after the previous task, so that pupils will be better focused on what the task is aimed at. In the previous task, they thought about what caused the movement of the various objects, in this task the movement itself will be explored. The teacher will provide the pupils with a simple pendulum or guide them to construct one (see figure). He then leads the pupils to explore how the pendulum works (non-targeted observation to gain pendulum experience).

Based on task 1 inquiry, pupils try to draw a direction of force that acts on the pendulum bob and try to explain what causes the bob to oscillate up and down when it is triggered. Pupils observe when the pendulum bob accelerates and slows down and they try to explain what causes the bob to accelerate and slow down.

The teacher leads the pupils to realize that if the object accelerates, it must be caused by some force. If the object slows down, it must also be caused by a force that acts in the opposite direction. Finally, pupils should find out that both the acceleration and the deceleration of the bob are caused by the gravitational force that acts on all objects constantly.

Tasks 3–6

Pupils already partially explored how pendulum works, thus the teacher suggests to investigate how the pendulum could be swung faster or slower. Either he/she will immediately ask them research questions (Tasks 3, 4, 5 and 6) or first discuss with pupils what they would change on the pendulum to swing faster or slower. Finally, the discussion should lead to the identification of research questions as outlined in Tasks 3-6. Research questions in Tasks 3-6 are similar in nature, but they examine different variables that may affect the operation of the pendulum. The teacher can divide the pupils in the class into four groups, while each group examines the influence of different variable on the oscillation rate. However, it is suitable to explore the influence of all variables in all groups, especially because the results are quite surprising for pupils.

It is important to make predictions before practical investigation. The teacher will present a research question, he can write it on the board to make it for pupils clear what the purpose of the research is. To target pupils‘ attention, it is suitable to discuss the proposed predictions. The predictions are pre-formulated in the task, so it is easier for pupils to predict – they just decide for one of them. This form of making predictions creates a pattern for pupils in how it is appropriate to formulate the predictions. Also, we emphasize that when investigating it is fine, if we do not agree in the predictions, we know that we are going to investigate a polemical thing, i. we are wondering how it really is. Thus, the variety of predictions is natural and we are not talking about bad and good predictions; we are talking only about confirmed and unconfirmed predictions. Once the predictions are made, it is suitable to discuss how to find out whether a pendulum with a longer or shorter string oscillates faster. This challenge is an interesting challenge for pupils. If the teacher has enough time, he will encourage the pupils in the groups to try to figure out a way by which we can distinguish in a sufficiently credible way whether the pendulum is swinging faster or not. If pupils devote themselves to designing procedures, it is important to discuss them and to select one that truly demonstrates the possible acceleration of pendulum vibration in an objective manner.

If the teacher has less time, he or she can suggest concrete procedure to pupils. In order to compare the results obtained from observation, it is important to determine the specific time period over which they will measure the number of pendulum oscillations. Since the pendulum can also oscillate relatively quickly, it is advisable to consider the movement of the pendulum bobs back and forth as one oscillation (swing). The teacher makes him/her sure that all pupils understand how the oscillation of the pendulum will be measured and determine. He/she suggest to count pendulum swings during 10 seconds.

Although the pendulum oscillation rate does not depend on how high the pendulum bobs are triggered (the pupils do not know it yet, task 6 is aimed at this variable), the teacher suggest the pupils to trigger the pendulum always from the same height. Because of the credibility of the measurement result, it is advisable for the teacher to lead the pupils to repeat the measurement three times for each pendulum. If some measurement was very different from the others, they do not take it into account in the evaluation, or repeat the measurement until the same (similar) results are obtained by multiple measurements. In this way, we teach students the patience and precision that belongs to scientific work, if we want to appeal to the results and thus trust them.

After creating the predictions and discussing the procedure by which pupils will be able to verify the predictions, pupils are dedicated to verifying the predictions. During the verification process, the teacher guides the pupils to a precise observation so that they can trust their results in the conclusion. Pupils enter the number of oscillations in the worksheet for a specified period of time (the teacher determines a suitable period of time based on which pendulums the pupils will use to subsequently convert the numbers into a diagram) – three measurements for each pendulum. The average number of oscillations (not by calculating the arithmetic mean, but estimating from three measurements for one pendulum) will be marked by the pupils in the diagram to highlight the observed differences. Subsequently, it is the task of the pupils to create a conclusion based on the results shown in the diagram, which includes the assessment of the predictionsand the answer to the research question. Referring to empirical data (measured values) is very important (in view of the development of great scientific ideas about science).