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# Example 2

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### Example 2

1. 1. Example 2 Theme: Introducing Science Learning Area: 1. Introduction to Science Learning Objective: 1.2 Understanding the steps in scientific investigation. Learning outcome: A student is able to: • state the steps in a scientific investigation/experiment, • carry out a scientific investigation/experiment. Materials: Sets of 8 activity cards - each printed with a step in a scientific investigation/experiment, string, pendulum bobs of different mass, retort stands and clamps, metre rules, protractors, wooden blocks, stop watches. Teacher: A very good afternoon to all of you. Let’s think about some of the things around us that you would like to know more about. Any ideas? Teacher waits and listens to the students' responses. Teacher: Everything that happens around us can be explained through science. In science we observe, test and make conclusions based on our findings. In primary school, we have learned how to carry out experiments. Let’s see if you can still remember the steps. Teacher introduces the activity and gives out 8 cards to each group. Written on each card is a step in a scientific investigation/experiment. Teacher: I would like you to arrange the cards in the proper order as in a scientific investigation or experiment. You have five minutes to do it. You may start now. Allow time for students to carry out the activity. Teacher: Can one of you read out the steps that you have arranged? Teacher calls a name (student A) and listens to his/her response.
2. 2. Teacher: Good! Teacher shows a transparency on the steps in a scientific investigation/experiment. a) determining ‘what I want to find out’ (identifying the problem), b) making a smart guess (forming a hypothesis), c) planning how to test the hypothesis (planning the experiment) • identify the variables, • determine the apparatus and materials required, • determine the procedure to carry out the experiment, method to collect and analyse data. d) carrying out the experiment, e) writing down what has been observed (collecting data), f) finding a meaning for what has been observed (analysing and interpreting data), g) deciding whether the hypothesis is true (making conclusions), h) writing a report on the investigation (reporting). Teacher: Now that we already know the steps in a scientific investigation. Let’s follow these steps in carrying out an experiment. Teacher shows a pendulum. Teacher: What do you call this? Waits for student’s response. Teacher: A good try! Actually this is called a pendulum. A pendulum is any mass that swings back and forth on a rope, string or chain. Where can you find this in everyday life? Teacher waits and listens to students’ reply Teacher: Good, pendulums can be found in ‘grandfather clocks’. A swing is also a pendulum. Teacher fixes the pendulum to the retort stand and pulls the mass away from its rest position, so that the string is at an angle, and then let go. The
3. 3. mass will begin to swing back and forth. Teacher shows the swinging of the pendulum. Teacher: Now I am going to pull the mass away from its rest position, so that the string is at an angle, and then let go. Tell me what you observe. Waits for student’s response. Teacher: Yes, the mass swings back and forth. This movement is called one complete oscillation. The time taken for the mass to swing back and forth once, is called the period of oscillation. Teacher demonstrates ‘one oscillation’ of the pendulum. Teacher draws the diagram on the board to show ‘one complete oscillation’. Teacher: What do you want to find out? (identifying the problem) If students cannot give the right answer, the teacher asks: Teacher: Do you think we can change the period of oscillation? (identifying the problem) Teacher waits and listens to students’ responses. Teacher: What do you think may affect the period of oscillation? Teacher waits and listens to students’ responses. Teacher writes student’s suggestion on the board. (mass of the pendulum bob, length of the pendulum, angle from the rest position) Teacher: Right, the period of oscillation may be affected by the mass of the pendulum bob, length of the pendulum, angle from the rest position. Now based on the problem that you have identified, I want you to form a hypothesis. Teacher waits and listens to students’ responses. Teacher: Now tell the class the hypothesis that you have formed. Teacher asks a few students to answer and write their suggestions on the board.
4. 4. Teacher: Yes, very good. Here are three hypotheses that you have suggested: • the bigger the mass of the pendulum bob, the longer the period of oscillation • the bigger the angle from the rest position, the longer the period of oscillation • the longer the pendulum, the longer the period of oscillation. Teacher: Now, get into your group and plan how you would test each hypothesis. I want a few groups to present your plan to the class. (planning the experiment) Allow students time to plan the experiment. All right, now can we have the first group to present their plan. I want the rest of you to note : (i) what they are going to change, what they are going to keep the same and what they are going to measure. (identifying variables) (ii) what apparatus and materials are required, (iii) the steps they are going to take, (iv) how to collect and analyse data. Teacher asks the first group to make their presentation. Teacher: We have to ensure our results are accurate. So what do we have to do? Teacher listens to students' suggestions. Teacher: Very good! You have to repeat your tests and take at least 3 readings. Well, this is what we gather from the class presentations. Let’s go through it once again. List of apparatus and materials needed for the experiment: • 1.2 metre string
5. 5. • 3 or 4 pendulum bobs of different mass • retort stand and clamp • metre rule • protractor • wooden blocks • stop watch Teacher: Hypothesis I The bigger the mass of the pendulum bob, the longer the period of oscillation. Manipulated variable: mass of the pendulum bob Responding variable: period of oscillation Fixed variable: number of oscillations, angle from the rest position, length of string, type of string. Data to be collected: i. mass of the pendulum bob ii. time taken for 10 oscillations Analysing the data: Period of oscillation = time taken for 10 oscillations 10
6. 6. Teacher: Hypothesis II The bigger the angle from the rest position, the longer the period of oscillation. Manipulated variable: angle from the rest position Responding variable: period of oscillation Fixed variable: number of oscillations, length of string, mass of the pendulum bob, type of string. Data to be collected: i. angle from the rest position ii. time taken for 10 oscillations Analysing the data: Period of oscillation = time taken for 10 oscillations 10 Teacher: Hypothesis III The longer the pendulum, the longer the period of oscillation Manipulated variable: length of string Responding variable: period of oscillation Fixed variable: number of oscillations, angle from the rest position, mass of the pendulum bob, type of string. Data to be collected: i. length of string ii. time taken for 10 oscillations Analysing the data: Period of oscillation = time taken for 10 oscillations 10 Teacher: Now, each group please get the apparatus and materials required and begin your experiment. You have 30 minutes to do the
7. 7. experiment. Well, go ahead with it but once you have gathered your data I want you to write your data on the board and we can have a look at the results together. Students carry out the experiments and teacher facilitates the activity. When they have written the results on the board, teacher gathers the students to discuss their findings Teacher: In analysing and interpreting data, let’s look at the table of results. Can any one make any inference from the data? Students give their ideas and teacher writes them on the board and decides on the statements that best shows the meaning of the results. Teacher: From your readings you have said that: (i) the period is the same for different masses of the pendulum, (ii) the period is the same for different angles from the rest position, (iii) the period is not the same for different lengths of the string. Teacher writes the students’ statements on the board. Teacher: Finally, we have come to the conclusion that the period of oscillation is dependent on the length of the string. Now, you are going to report your experiment. Discuss in your group how you would present it. You have 5 minutes to do so. Allow students time to discuss and have one group present their framework. Teacher: Date Problem identified: Hypothesis: Materials and Apparatus: Method: Precautions:
8. 8. Data collected: Conclusion. Please remember to draw accurate diagrams and label them. I would like you to pass up your report tomorrow. Any questions? Teacher waits and listens to student’s response. Teacher: OK class, make sure that the materials and apparatus are returned to their respective places and your tables are clean. See you in the next lesson.