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Example 2

Theme: Introducing ScienceLearning Area: 1. Introduction to ScienceLearning 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 scientificinvestigation/experiment, string, pendulum bobs of different mass, retortstands and clamps, metre rules, protractors, wooden blocks, stopwatches.

Teacher: A very good afternoon to all of you. Lets think about some of thethings around us that you would like to know more about. Anyideas?

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 onour findings.In primary school, we have learned how to carry out experiments.Lets 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 ascientific 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.

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Teacher: Good!

Teacher shows a transparency on the steps in a scientificinvestigation/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. Lets follow these steps in carrying out anexperiment.

Teacher shows a pendulum.Teacher: What do you call this?

Waits for students response.Teacher: A good try! Actually this is called a pendulum.

A pendulum is any mass that swings back and forth on a rope, stringor chain. Where can you find this in everyday life?

Teacher waits and listens to students replyTeacher:

Good, pendulums can be found in grandfather clocks. A swing isalso a pendulum.Teacher fixes the pendulum to the retort stand and pulls the mass awayfrom its rest position, so that the string is at an angle, and then let go. Themass 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 students response.

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Teacher: Yes, the mass swings back and forth. This movement is called onecomplete oscillation.The time taken for the mass to swing back and forth once, is calledthe period of oscillation.

Teacher demonstrates one oscillation of the pendulum.

Teacher draws the diagram on the board to show one completeoscillation.

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 ofoscillation?(identifying the problem)Teacher waits and listens to students responses.

Teacher: What do you think may affect the periodof oscillation?

Teacher waits and listens to students responses.

Teacher writes students 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 thependulum bob, length of the pendulum, angle from the rest position.

Now based on the problem that you have identified, Iwant 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 theirsuggestions on the board.

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 eachhypothesis. I want a few groups to present your plan to theclass.(planning the experiment)

Allow students time to plan the experiment.All right, now can we have the first group to present their plan. I wantthe 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,

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(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 todo?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. Lets go through it once again.List of apparatus and materials needed for theexperiment:

1.2 metre string 3 or 4 pendulum bobs of different mass retort stand and clamp metre rule protractor wooden blocks stop watch

Teacher: Hypothesis IThe bigger the mass of the pendulum bob, the longer theperiod of oscillation.

Manipulated variable: mass of the pendulum bob

Responding variable: period of oscillation

Fixed variable: number of oscillations, angle from the restposition, length of string, type of string.

Data to be collected:

i. mass of the pendulum bob

ii. time taken for 10 oscillationsAnalysing the data:

Period of oscillation = time taken for 10 oscillations

10

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Teacher: Hypothesis IIThe bigger the angle from the rest position, the longer the period ofoscillation.Manipulated variable: angle from the rest position

Responding variable: period of oscillation

Fixed variable: number of oscillations, length of string, mass of thependulum bob, type of string.Data to be collected:

i. angle from the rest position



10Teacher: Hypothesis III

The longer the pendulum, the longer the period of oscillation Manipulated variable: length of string

Responding variable: period of oscillationFixed 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



10Teacher: Now, each group please get the apparatus and materials required

and begin your experiment. You have 30 minutes to do theexperiment.

Well, go ahead with it but once you have gathered your data I wantyou to write your data on the board and we can have a look at theresults together.Students carry out the experiments and teacher facilitates the activity.When they have written the results on the board, teacher gathers thestudents to discuss their findings

Teacher: In analysing and interpreting data, lets look at the table ofresults. Can any one make any inference from the data?

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Students give their ideas and teacher writes them on the board anddecides 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 yourgroup 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: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 students response.

Teacher: OK class, make sure that the materials and apparatus are returned totheir respective places and your tables are clean. See you in the nextlesson.

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