1. Scientific Investigation Science & Technology

2. Scientific Investigation2 Learning objectives: To identify the major steps in carrying out a scientific investigation To acquire the skills in performing a scientific investigation To collect, interpret, analyse and evaluate scientific information

3. Scientific Investigation3 Make Observations Stretch a rubber band with both hands and record your observations.

4. Scientific Investigation4 Make Observations When you stretch the rubber band with greater force, the rubber band will become longer. That is, there is a direct relationship between the applied force and the extension of rubber band.

5. Scientific Investigation5 Formulate a Hypothesis Based on your observations, formulate a hypothesis relating the applied force with the extension of an elastic material such as rubber band, spring.

6. Scientific Investigation6 Formulate a Hypothesis The force exerted by a spring (an elastic material) is proportional to the distance the spring is stretched or compressed from its relaxed position. F  x F: applied force (e.g. weight ) x: extension of the spring

7. Scientific Investigation7 Formulate a Hypothesis x unstretched spring 2x F 2 F F  x It takes twice as much force to stretch a spring twice as far.

8. Scientific Investigation8 Test the Hypothesis Materials provided: spiral spring with pointer stand with an adjustable mirrored scale (15 cm) slotted weights (10 g, 20 g, 50 g) Design an experiment to test the hypothesis.

9. Scientific Investigation9 Test the Hypothesis Experimental design: Perform several measurements to collect a set of data correlating the weights and the extension of spring Plot a graph of weight vs. extension of spring to verify the formulated hypothesis F  x a plot of weight, F vs. extension, x should yield a straight line passing through the origin

10. Scientific Investigation10 Discussion Questions for Lesson 1 of Chapter 2 What do you observe when stretching a rubber band with your hands? Suggest some other scientific observations in your daily life. What is a hypothesis? How would you formulate a hypothesis?

11. Scientific Investigation11 Suggested Answers for Questions (Lesson 1) What do you observe when stretching a rubber band with your hands? When you stretch the rubber band with greater force, the rubber band will become longer. Suggest some other scientific observations in your daily life. Any free object will be falling downward due to gravity A wooden block will float on water while a metal block will sink

12. Scientific Investigation12 Suggested Answers for Questions (Lesson 1) What is a hypothesis? A tentative explanation of a scientific question based on observations and past knowledge How would you formulate a hypothesis? Formulating a hypothesis involves inductive reasoning

13. Scientific Investigation13 Test the Hypothesis (Suggested Procedure) 1.Set up the apparatus as shown in the figure.

14. Scientific Investigation14 Test the Hypothesis (Suggested Procedure) 2.Record the starting position of the spring at its relaxed state as indicated by the marker. 3.Add 20 g slotted weight to extend spring to a measurable displacement (x). Record the weight and the length of spring to calculate the extension x.

15. Scientific Investigation15 Test the Hypothesis (Suggested Procedure) 4.Repeat Step 3 for 4 more trials using different weight loads (e.g. 40 g, 60 g, 80 g, 100 g).

16. Scientific Investigation16 Test the Hypothesis (Results) Weight, F (g) Length of spring (cm) Extension of spring, x (cm) 000 201.0 402.0 603.0 804.0 1005.0

17. Scientific Investigation17 Test the Hypothesis (Results)

18. Scientific Investigation18 Draw Conclusion Would you accept or reject the hypothesis? Why?

19. Scientific Investigation19 Draw Conclusion When the plotted graph is a straight line passing through the origin, there is a direct proportionality between the weight load (F) and the extension of a spring (x), i.e. F  x. Hence, the hypothesis can be accepted. If the plotted graph is not a straight line, the hypothesis should be rejected.

20. Scientific Investigation20 Discussion Questions for Lesson 2 of Chapter 2 Describe briefly the steps required in order to test a hypothesis. What is the purpose of drawing conclusion in a scientific investigation?

21. Scientific Investigation21 Suggested Answers for Questions (Lesson 2) Describe briefly the steps required in order to test a hypothesis. Perform an experiment to collect, interpret, analyse, and evaluate the data Repeated experiments and control experiments are required

22. Scientific Investigation22 Suggested Answers for Questions (Lesson 2) What is the purpose of drawing conclusion in a scientific investigation? A conclusion is a statement whether the results support or falsify the hypothesis Science progresses and the hypothesis may have to be modified in the future

23. Scientific Investigation23 Overall Conclusion – Scientific Investigation Make observations Formulate a hypothesis Test the hypothesis Draw conclusion

24. Scientific Investigation24 Mind Map – Scientific Investigation framed as a reveals some leads to tested by gathering data in an may lead to more may lead to a Careful observation(s) Pattern Conclusion Experiment Hypothesis Question(s)