Enhancing Thinking Skills in Science Context Lesson 5

1. Enhancing Thinking Skills in Science ContextLesson 5 Double--blind Design in Randomised blind Experimental Design

2. Activity 1 To study the effect of coffee on humans’ concentration power

3. Hypothesis: Coffee may enhance the concentration power of humans.

4. Materials and apparatus • 1 packet of coffee A • 1 packet of coffee B • Enough hot water (at 800C ) for about 45 paper cups (half full) • 1 bottle of coffee creamer • 50 spoons • 1 bag of red rice (net weight: 1.5 kg) • 1 bag of white rice (net weight: 2 kg) • 45 Petri dishes • 45 Heat resistant paper cups

5. Procedure: a) The class is randomly divided into three groups (A, B and C), each of which consisting of roughly the same number of students. b) Each of you will be given a Petri dish containing well--mixed red and mixed rice in the ratio 2:1 (approx.). c) Each of you is required to pick out the red rice from the white rice by hand at constant speed. d) Each of you is required to record down the number of red rice picked up in five minutes. e) Record down the total no. of red rice picked up by the different groups of students in five minutes. f) Then each group will be given drinks according to their group number immediately after step (e):

6. Group A: coffee A + coffee creamer [Drink A] (3 spoonful of coffee A + 2 spoonful of coffee creamer +half cup of hot water (800C) + stirring) Group B: coffee B + coffee creamer [Drink B] (3 spoonful of coffee B + 2 spoonful of coffee creamer + half cup of hot water (800C) + stirring) Group C: water + coffee creamer [Drink C] (2 spoonful of coffee creamer + half cup of hot water (800C) + stirring)

7. Procedure: (g) Thirty minutes after taking the drinkeach of you will be each of you will be required to repeat steps (b), (c), (d) and (e).

14. Result Group A (Taken Drink A)

15. Result Group B (Taken Drink B)

16. Result Group C (Taken Drink C)

17. Task: 1. Why was the experiment repeated? (i.e. why do we need to do the first counting experiment and then do the second experiment? )

18. Task: 2. Why was the second experiment carried out 30 minutes after taking the drink?

19. Task: 3. Pool the group and class data after the experiment. You may need to do some calculation in order to obtain more conclusive result. Show the details of your treatment of the class data.

20. Task: 4. Compare the results of group A, B and C obtained from (3).Does the result obtained support the hypothesis that coffee may enhance the concentration power of humans? Please explain your answers.

21. The following data of the above experiment was obtained from 3 classes (105 Secondary 2 students) of a school. Compare the results and try to draw a conclusion.

22. Class data obtained from 2A, 2B, 2C

25. Discussion of Experimental Results a) Standard deviation indicates how spread out a set of data is, that is, whether the data are relatively close together and clustered around the mean or spread out. b) Referring to the standard deviation difference of Class 2A, 2B and 2C the difference in standard deviation of Class 2B is the greatest for Drink A and Drink B, which makes the data collected in class 2B not so trustworthy. However, the differences in standard deviation of class 2A and 2C are reasonable. Hence, the result of Class 2B was discarded but the results of Class 2A and 2C are combined to see whether there is any significant evidence for drawing a conclusion.

28. Drink B is decaffeinated coffee • It contains nearly no caffeine (only 0.1% caffeine). • It was supposed to be used as a placebo.

29. A Double--blind Study • A double-blind study, relatively easy to achieve in drug studies, belongs to the category of Randomised Experimental Design. Two similar groups of people (experimental and control) act as targets of the study. The experimental group is given an actual treatment (e.g. an investigational drug) while the control group is given a placebo (may be a sugar pill), which has identical appearance (e.g. colour, taste, size) as the investigational drug. • A placebo is a preparation which is pharmacologically inert but which may have a medical effect solely on the power of suggestion, a response known as the placebo effect.

30. A Double--blind Study • Furthermore, people are randomly assigned to the control or experimental group and given random numbers by a study co-ordinator, who also encodes the investigative drug and the placebo with matching random numbers. Neither the experimental subjects (both the control and experimental group) nor the researchers monitoring the outcome of the study know who is receiving which treatment (the investigative drug or the placebo), until the study is over and the random code is broken. Such an arrangement would prevent the subjects from biasing the result by knowing which group they are in.

31. A Double--blind Study • If later it is found that results from the experimental group is better than that of the control group, the treatment or the drug given to the experimental group is assumed to have an effect. • Finally, the same experiment (study) need to be replicated on a large group of subjects in order that more significant conclusion can be drawn about the effect of the investigative drug.

33. Discussion Questions 1) Is the experimental design a double-blind design? Explain your answer. 2) Is the experimental design a valid design? Explain your answer. 3) If the experimental design is not a valid one, suggest ways to improve the experimental design

34. Suggested answers: • Is the experimental design a double-blind design? Explain your answer. The experimental design is a single-blind , not a double-blind because the teacher knows the details of the drink and which group of students would take which drink.

35. 2) Is the experimental design a valid design? Explain your answer. Judging from the Percentage Increase (Mean) of Drink A, B and the Control of Class 2A and 2C the experimental design is not a valid design. Possible reasons may be as follows: • The sample size is too small; • The suggested method is not a valid method to measure the concentration power of humans; • Some students may drink coffee during lunch or breakfast and hence may interfere with the experimental result • Some students are more skillful at doing such task requiring good motor skills; • The effect of coffee is not significant because the “dose” is not enough.

36. 3) If the experimental design is not a valid one, suggest ways to improve the experimental design? Ways to improve the experimental design may be as follows: • To increase the sample size (invite more classes to do the experiment); • To use another method to measure the concentration power of the experimental subjects, e.g. Use photographic memory method (eidetic imagery, in which a person memorises details of a complex scene at a glance) to measure the concentration power of the experimental subjects • Scattered numerals would appear for up to two-thirds of a second in the computer screen and were then masked by white squares. • Each student is required to write down the numerals on a worksheet according to their previous location within a fifth of a second. • The same procedure with 10 different sets of numerals repeats for 10 times and the students would check the answers after the activity. • The percent accuracy of each student is counted and then the sum, the mean, percentage increase, standard deviation are collected for comparison among the three groups of students drinking the control, drink A and drink B. as before.