N2 Cluster Workshop

1. N2 Cluster Workshop Answering Open-ended Questions 11 April 2008

2. Overview of programme:

3. Objectives: • To be equipped with a strategy to answer open-ended questions. • To learn to assign and award marks accordingly. • To apply an answer key for marking.

4. Why is it so important to have a good answer key?

5. A good Answer Key • guides us in our marking which is to be standardised • lists all acceptable and unacceptable answers • guides us in the way we teach by clearly stating expectations

6. Answer Key (Science) Type of Examination : * P3 / P4 Year : 200_ * P5 / P6 (* Merged / Foundation Programme) * CA1 / SA1 / CA2 / SA2 / Prelim (* Delete accordingly) Multiple Choice Questions

7. Open-ended questions • Bold denotes key words while underline denotes key concept • Award full marks for a question/part question when the idea/concept is correct. • Do not award any marks if the answer expresses a wrong idea/concept. • Do not deduct any mark for an answer that is not well expressed or has grammatical errors, provided the idea/concept is correct. • If more points are given over and above the number required, award marks for the correct points and deduct ½ mark for each wrong idea/concept in the additional points.

8. What are the steps a pupil should take in order to be ‘on target’?

9. The pupil should • Read question carefully • Decide on topics/concepts • Select suitable words/phrases • Put down on paper

10. Sun Earth • A Sample 1 Explain why only part of the Sun can be seen at Position A. • Underlying concepts: • Opacity of material (in this case, the moon) • Source of light • Light travels in a straight line

11. Possible answer: The moon is between the sun and the earth. It blocks the light from the sun and casts a huge shadow on part of the earth’s surface. Thus, only part of the sun can be seen at Position A.

12. Sample 2 An experiment was carried out with 20 mealworms. The mealworms were placed in the centre of a tray as shown in the diagram below. A different type of food was placed at each corner of the tray.

13. After a while, the number of mealworms at each corner was counted. The results were recorded in the table below. • What is the aim of this experiment? • State two things that must be kept the same for this experiment to be a fair test.

14. Underlying concepts: • Fair test (control of variables) • Possible Answers • The aim of this experiment is to find out which type of food mealworms prefer/like the most • The amount of each type of food used, the distance of each type of the food from the initial position of the mealworms

15. Sample 3 Equal amounts of water were poured into two containers of identical mass. The containers were then placed on a scale. They balanced each other as shown in the diagram below.

16. The set-up was left in a windy place. After one day, one of the containers of water was found to be lighter than the other. • Which container was lighter? • Explain your answer in (a). • How would the result of the experiment be affected if the set-up was left in a place with no wind?

17. Underlying concepts: • Rate of evaporation • Exposed surface area • Possible Answers • Container A • Container A has a larger exposed surface area. So, the rate of evaporation is higher and more water evaporated from Container A. • Both containers would lose less water or Less water will evaporate from each container.

18. Sample of Pupils’ Answers By Asma

19. Question 1 Write down the steps in an experiment to show that ‘Earthworms prefer moist to dry environment.’ Pupil’s Response: Take one dry towel on the left side and another wet towel and put it on the right side. Then put the earthworms down and let them crawl. If they crawl to the wet towel, it means that they prefer moist to dry environment.

20. Question 1 Write down the steps in an experiment to show that ‘Earthworms prefer moist to dry environment.’ Expected Response: • Place dry soil in half of a tray. • Place an equal amount of moist soil in the other half of the same tray. • Place some earthworms in the middle of the tray. • Cover the tray and wait for a few minutes for the earthworms to move to the preferred environment. • Observe the location of the earthworms. • Repeat the experiment at least 3 times. • Conclusion : Most if not all the earthworms will be found where the moist soil is. This shows that earthworms prefer moist to dry environment.

21. Question 2 Some fish were placed in a transparent glass jar shown below. It was found that the fish swam near the surface most of the time. What is the most likely reason for the fish to behave this way?

22. Pupils’ Response • It was because the nearer the fish is to the surface, the more air they will get. • The fish swim near the surface to get oxygen. • The fish need to breathe oxygen, so they swim to the surface for it. • They want more oxygen. • There is too little oxygen in the jar. • It is to find oxygen. • It is to take oxygen from the surrounding air. • There is no oxygen in the water.

23. Expected Response • There is insufficient dissolved oxygen in the water. The fish swim nearer the surface to get more dissolved oxygen.

24. Question 3 Kamal dug a hole in the school garden and prepared the set-up below to obtain fresh water from the pond water. He left the set-up out in the Sun for a day. Explain how Kamal could get fresh water from this set-up.

25. Pupils’ Response: • The pond water will evaporate all the salt and it will become freshwater. • Water will evaporate and condense on the plastic sheet. • The pond water will evaporate and water droplets will form on the plastic sheet. Expected Response: Water evaporates to form water vapour. When the water vapour meets the cooler surface of the plastic sheet, it condenses to form water droplets which will then drop into the cup.

26. Question 4 Jane puts the empty glass bottle with a tight fitting stopper into a basin of warm water. Explain clearly why the stopper pops out from the bottle. stopper empty glass bottle

27. Pupils’ Response • Heat causes air to push the stopper out. • Expansion of air causes it. Expected Response: Warm waterheats up the air in the bottle. Air expands when heated and this cause an increase in volume, making the stopper pop out from the bottle.

28. Question 5 Terence put some fish in a bowl of water. Then he put in some duckweeds. He observed them for a week and kept a daily record of the number of duckweeds in the bowl. He drew a graph below. Number of Duckweeds 1 2 3 4 5 6 Days

29. Question 5 What effect does the dropping have on the duckweeds? Pupils’ Response: • The droppings fertilise the duckweeds. • The plant can change the droppings into nutrients. • It is nutrients for them to photosynthesise. • It acts as fertilisers to the duckweeds. Expected Response: They provide nutrients for the duckweeds, enabling them to grow in numbers.

30. Awarding marks By Mei Lin

31. Science Marking Scheme for Booklet B • A maximum of half mark per question is deducted for spelling errors of key words.

32. Sample Question 1 Jim said, “When a glass of cold water is taken out of the refrigerator, it becomes warmer because it loses coldness to the surroundings.”Do you agree with Jim’s statement? Support your answer with an explanation. (2 marks) I disagree. The water becomes warmer because it gains heat (1m) from the surroundings (1m) / heat travels (1m) from the surrounding air to the cold water. (1m)

33. Science Marking Scheme for Booklet B • For some questions, part (a) & part (b) are related. If part (a) is wrong, no marks for part (b).

34. Sample Question 2 Look at the diagram of a cell below. (a) Is this a plant or animal cell? (1 mark) Plant cell. (1m) (b) In which part of a plant or animal would you find this cell? (1 mark) Root / Bark(1m) (Do not mark part (b) if part (a) is wrong)

35. Science Marking Scheme for Booklet B • For some questions, a fixed number of answers are required. If more than the required number of answers are given, no marks will be awarded.

36. Sheet A Sheet C Sheet D Sheet B torch Sample Question 3 Jenny carried out the following experiment in a dark room. Sheets A, B, C and D are arranged in a straight line. A star-shaped hole is punched in Sheet A. When the torch is switched on, a bright star patch of light is seen on Sheet C only. Jenny is sure that two of the sheets are opaque. Which two of the four sheets is she referring to? (2 marks) Sheet A and Sheet C. (1m each. 0m if more than 2 answers are given.)

37. Science Marking Scheme for Booklet B • For questions with parts independent of one another, each part is assigned a mark.

38. Sample Question 4 Read the statements below and indicate whether each of the statements is True or False. Put a tick (√) in the correct box. (2 marks) (½ mark each)

39. Science Marking Scheme for Booklet B • For questions with parts dependent on one another, the answers are marked in totality and will be awarded as full marks if completely correct or zero if any part is wrong.

40. Sample Question 5 Jason wants to see his cheek cells under a microscope. However the following instructions on what he needs to do are not in the correct order. Step A: Gently mount a cover slip over the scrapings. Step B: Scrape some cells from the inside of the cheek using a toothpick. Step C: Use a toothpick to spread the scrapings onto a microscope slide. Put the instructions in the correct order by filling the letters A, B and C in the boxes below. (2 marks) (2m or 0m)

41. Q & A

42. Summary of Cluster Events for 2008

43. Thank you for being here!