WOODGROVE PRIMARY SCHOOL SCIENCE DEPARTMENT SCIENCE PARENTS WORKSHOP 2013 SCIENCE ANSWERING TECHNIQUES

WOODGROVE PRIMARY SCHOOL SCIENCE DEPARTMENT SCIENCE PARENTS WORKSHOP 2013 SCIENCE ANSWERING TECHNIQUES

An Overview of the overall Primary Science Syllabus 2008 Themes Diversity Cycles Systems Lower Block (Primary 3 and 4) General characteristics and classification of living and non-living things Properties and uses of materials Life cycles of plants and animals Matter Plant parts and functions Digestive system Upper Block (Primary 5 and 6) Reproduction of plants and animals Water Respiratory and circulatory systems in Plant Respiratory and circulatory systems in Human Cell system Electrical system Interactions Magnets Frictional force, gravitational force, force in springs Characteristics of environment Habitats and communities Food chains and food webs Adaptations Man s impact on environment Energy Light energy Heat energy Kinetic energy, Potential energy, Sound energy Photosynthesis and Respiration Energy conversion

Assessment Year Plan on School Website http://www.woodgrovepri.moe.edu.sg

ELIMINATION METHOD (MCQ)

Elimination Technique Basically means to look at the options and to use logical reasoning to remove obvious distractors. Encourage your child to do working by using ticks ( ), (T) for True, (NT) for statements that are not true or (F) for False statements

Elimination Technique Wei Shian wanted to purchase a new pair of glasses. He conducted an investigation to find out which type of glass surface was the most scratchproof. He rubbed 4 surfaces A, B, C and D, each with a toothbrush. Then he observed each surface with a magnifying glass. He noticed scratches on the surfaces as shown below. Arrange the hardness of the following surfaces A, B, C and D in ascending order. (1) B, D, C, A (2) X A, D, C, B (3) B, X C, D, A (4) X A, C, D, B X X X Most scratches softest B Least scratches hardest A Answer: (1)

AIMS & VARIABLES

What is an aim? The objective of the experiment/ the reason why we wish to carry out the experiment. Use phrases like To find out how / To investigate how as a starter E.g: To find out how the number of turns wound round an iron nail affects the magnetic strength of the iron nail when it becomes an electromagnet.

Variables A variable is any factor, trait, or condition that can exist in differing amounts or types. An experiment usually has three kinds of variables: independent, dependent, and controlled. Independent variable: Changed variable (Cause) Controlled variables: Constant variables Dependent variable: Result/ Effect due to the changed variable

Changed Variable Aim To find out how (Cause/ Changed variable) affects the (Effect/ Result) Identify the difference/ changed variable in the experiment to determine the aim

Sally conducted an experiment on germination of seed as shown below. She placed a green bean on the wet cotton wool in the test tube in each set-up. Set-up A, was placed in the cupboard and Set-up B was placed in the refrigerator. Step 1: What are the conditions for germination? Warmth Oxygen Water Step 2: Circle the difference/ changed variable between the two set-ups? Step 3: Location/ venue of experiment temperature presence/ amount of warmth

Aim of the experiment: To find out how different locations/temperature/ amount/ presence of warmth affects the germination of seeds. Result Changed variable

Fair Test (Scenario 1- Why is it a fair test?) Q: Why is this experiment a fair one? In a fair test, only one variable can be changed so that we can confirm that any difference in the (result) is due to the (changed variable).

Example Scenario 1- Why is it a fair test? Changed variable Result (height of plant) Betty wanted to find out what type of soil was the most suitable for growing balsam plants. She planted 3 balsam plants of similar size in three pots, X, Y and Z. The three pots were placed for the same duration at the same location in the garden. Pot X Pot Y Pot Z Material of pot plastic plastic plastic Type of soil garden soil sand clay Size of pot 1500 cm 3 1500 cm 3 1500 cm 3 Amount of water used each day 200 cm 3 200 cm 3 200 cm 3 Q: Why is the above experiment a fair one? In a fair test, only one variable can be changed so that we can confirm that any difference in the height of the plant (result) is due to the type of soil (changed variable).

Fair Test Scenario 2 (How will keeping this variable constant make it a fair test?) Q: How does making (the variable which remains constant) the same makes it a fair test? Only one variable was changed so that we can confirm that any difference in the (result) is due to the (changed variable) and not (state the variable kept constant in the qns stem).

Fair Test Scenario 3 (Why is this not a fair test?) Q: Why is the above experiment NOT a fair one? More than one variables were changed so we cannot confirm that any difference in the (result) is due to the (changed variable) or (the other variable changed).

Example Scenario 3- Why is this not a fair test? Changed variable Betty wanted to find out what type of soil was the most suitable for growing balsam plants. She planted 3 balsam plants of similar size in three pots, A, B and C. The three pots were placed for the same duration at the same location in the garden. Pot A Pot B Pot C Material of pot plastic plastic plastic Type of soil garden soil sand clay Amount of soil 1500 cm 3 1000 cm 3 500 cm 3 Amount of water 200 cm 3 200 cm 3 200 cm 3 used each day Why was the above experiment NOT a fair one? What is the aim? What should be the changed variable? What variables were changed? Type of soil Type of soil Amount of soil

Fair Test Scenario 3 (Why is this not a fair test?) Q: Why is the above experiment NOT a fair one? More than one variables were changed so we cannot confirm that any difference in the height of the plant (result) is due to the type of soil (changed variable) or the amount of soil (the other variable changed).

Fair test- Scenario 4 (Identifying or stating which variables should be kept constant) Usually a table with variables will be given and pupils are required to tick the variable(s) to be kept constant What is the aim? Choose only 1 changed variable that will affect my result

Changed variable Raymond wanted to find out how the type of liquid in which the beans are soaked in affects their growth. State in the table below if the following variables should be kept constant or changed to ensure that the experiment would be a fair one. Put a tick ( ) in the appropriate boxes. Variable Amount of time in which the beans were soaked for Type of liquid in which the beans were soaked in Amount of liquid in which the beans were soaked in Temperature of liquid in which the beans were soaked in To be changed To be kept constant

What is a control in experiments? Provides a baseline to measure other results against. It is to compare and confirm that any difference in the (result) is due to the (changed variable) and not (other variables).

Control Scenario 1 (What is the purpose of the control set-up?) John immersed 4 similar lengths of fabric strips made from different materials into 4 similar containers containing 200ml of water at room temperature as shown below. He left the five containers at the same location. He recorded his results in the table below. Fabric A Fabric B Fabric C Fabric D 200ml of water at room temperature 200ml of water at room temperature Amount of water in the container in the beginning (ml) Amount of water in the container at the end (ml) Container with fabric A Container with fabric B Container with fabric C Container with fabric D Container without any fabric 200 200 200 200 200 118 88 148 198 198

What is the purpose of setting up the container without any fabric? It is to compare and confirm that any difference in the amount of water the left in the container (result) is due to the absorbency of the materials (changed variable) and not the evaporation of water (other variables).

Control Scenario 2 (Choosing of set-ups for a fair test and explaining why) Jane wanted to find out if roots absorb water. She set up four experimental set-ups as shown below. Which two set-ups should Jane choose for her experiment to ensure that it is a fair one? Explain why.

Jane wants to find out if roots absorb water. There are four set-ups given below. Step 1: Identify the aim Aim Changed variable Presence of roots Step 2: Visual comparison (by ticking) or table comparison Setup Plant with roots Water Oil A B C D Answer: Setup B and Setup C

Jane wants to find out if roots absorb water. There are four set-ups given below. a)which two setups should Jane choose for her experiment? [1m] b)explain why. [2m] Set-ups B and C. This is to compare and confirm that any difference in the volume of water left in Beaker C is only due to the absorption of water by the presence of plant roots and not evaporation. plant Oil layer water Oil layer water Setup B Setup C

Control- Scenario 2 (Why is the conclusion inaccurate?) Jonathan carried out an investigation to find out how the adding of fertiliser affects the growth of a plant. He set up the experiment as shown below and concluded that the plant grew better with fertiliser added. Set up A Set up B Set-ups Type of plant Type of soil Amount of fertiliser Location Difference in height of plant A Rose plant Garden soil 100 ml In the garden 10cm B Rose plant Garden soil 250ml In the garden 20cm Jonathan s father said that his conclusion was inaccurate. Explain why this is so. What should Jonathan do to make sure that his conclusion is correct?

Answer Set-ups Type of plant Type of soil Amount of fertiliser Location Difference in height of plant A Rose plant Garden soil 100 ml In the garden 10cm B Rose plant Garden soil 250ml In the garden 20cm Jonathan added fertiliser to both setups. Hence, he could not confirm if the differences in the height of the plants were due to the adding of fertiliser or the amount of fertiliser. What should Jonathan do to make sure it is a fair test? He should not add fertiliser to one of the set-ups.

RELATIONSHIP & GRAPHS

Statement to describe relationship As increases/ decreases, (cause) also increases/ decreases. (effect)

Relationship graph P3 Magnets (Cause) Johnny wants to find out how the number of coils round an iron nail affects the strength of the electromagnet. (Effect) He recorded the findings in the table below. Number of coils Number of paper clips attracted 4 5 8 10 12 15 Based on the results what can you conclude about the relationship between the number of coils and the strength of the electromagnet? (Cause) As the number of coils increases, the strength of the electromagnet increases. (Effect)

Relationship graph P4 Light (Cause) Johnny wants to find out how the number of sheets of paper between the torch and light sensor affects the amount of light received by the sensor. He set up the experiment as shown. (Effect) He recorded the findings in the table below. Number of Amount of light paper sheets (units) 0 80 1 32 2 13 3 5 4 2 5 1 6 0 7 0 torch X light sensor Connected to a meter Based on the results what can you conclude about the relationship between the number of paper sheets and the amount of light detected? As the number of paper sheets increases, the amount of light (Effect) (Cause) detected decreases.

Relationship graph y-axis (Effect) x-axis (Cause)

Relationship graph P3 Magnets x-axis (Cause) Johnny wants to find out how the number of coils round an iron nail affects the strength of the electromagnet. y-axis (Effect) He recorded the findings in the table below. Number of Number of coils paper clips attracted 4 5 8 10 12 15 Number of paper clips attracted (Effect) Direct relationship Number of coils

Relationship graph P3 Magnets x-axis (Cause) Johnny wants to find out how the number of sheets of paper between the torch and light sensor affects the amount of light received by the sensor. y-axis (Effect) He set up the experiment as shown torch X light sensor Connected to a meter He recorded the findings in the table below. Number of Amount of light paper sheets (units) 0 80 1 32 2 13 3 5 4 2 5 1 6 0 7 0 8 0 Amount of light/ units (Effect) inverse relationship Number of paper sheets

In summary Direct relationship Upward trend Inverse relationship Downward trend Cause Effect Graphical Trend Upward Downward

Comparative form The comparative form is used to describe differences between two objects/specimens/materials etc.. Use of comparative words like: more, less (e.g: gains more heat) adjective + -er (e.g: higher temperature difference, poorer conductor of heat, stronger material)

Superlative form The superlative is used to describe differences between three or more. Use of superlatives like: most, least (e.g: withstand the most number of weight before breaking) adjective + -est (e.g: greatest temperature difference, took the shortest time to reach 30 C)

Use CICA method to answer questions involving data interpretation. C Choice I Interpret from data (from graph/ table) C Conclusion (use comparative/ superlatives) A Application

Now try this: The absorbency of a material refers to the amount of water it can absorb. Michael conducted an experiment using four strips of similar size, length and thickness but were made from different materials A, B, C and D. He immersed an equal length of each strip of material into a dish containing coloured water for the same period of time. The diagram below shows the result of his experiment. Based on the results, which one of the materials is the most suitable for making a kitchen towel that will dry the plates? Explain your answer. C: Material C. [no marks] I: From the diagram, it absorbed the most amount of water. [1] C: Hence, it is the most absorbent. [½] A: It is most suitable for making a kitchen towel as it will absorb the most amount of water from the dishes to dry them. [½]

P4 : Heat John conducted an experiment and recorded his observation as shown in the table below. ice block Container made of with Material Material A Based on the results in the table, which material is the most suitable for making part X of a frying pan as shown? Explain your answer. C: Material A. [no marks] A B Average time taken to melt completely 1 h 30 min 3 h 05 min I: From the table, it took a shorter time for the ice to melt completely. [1] Part X C: Hence, it is a better conductor of heat. [½] A: It is most suitable for making part X of a frying pan as it gains more heat from the flame faster to cook the food. [½]

Comparing Graphs - gradient Gradient = Change in Y Change in X If the line is steeper, it has a larger gradient so there is a greater difference If the line is gentler, it has a smaller gradient so there is a lesser difference

Which line P or Q shows a greater increase in temperature over time? Temperature (ºC) P Q P - steeper slope greater change Q - gentler slope lesser change P has a greater increase in temperature over time. Time (min)

Which line, A and B shows a slower rate of evaporation? Amount of water (ml) Rate of evaporation = Change in amount of water Time A B Time (min) B gentler slope slower rate A steeper slope faster rate B has a slower rate of evaporation

Extension of spring Length of spring (cm) Spring A 80 60 Original length with no mass 40 20 20 40 60 80 Load (g) What is the extension of Spring A when 80g of mass was added? Extension of spring = New length - Original length Length of spring with 80g 80cm Original length of spring 20cm Extension of spring 80-20 = 60cm

Let s practise! The graph shows how the length of Daisy s shadow changes over a period of time as she walks in a straight line near a street lamp at night. Which section, X or Y shows Daisy walking at a slower speed? Explain.

Answer The graph shows how the length of Daisy s shadow changes over a period of time as she walks in a straight line near a street lamp at night. Which section, X or Y shows Daisy walking at a slower speed? X Ans: Lesser increase in length of shadow at X over same timing (2 seconds) than Y change for X change for Y

The diagram below shows three containers, P, Q and R with 100ml of water at room temperature. They were placed at the same location until all the water evaporated. Container P Container Q Container R Based on the diagrams above, draw three lines to show the different rates of evaporation for the three containers in the graph below. Label your lines. Volume of water (ml) Time (min)

What are the factors affecting rate of evaporation Wind Humidity Area of exposed surface Temperature Volume of water (ml) 100 Largest exposed surface area most water evaporates fastest rate of evaporation P Steepest gradient fastest rate of evaporation P Gentlest gradient slowest rate of evaporation Q 0 P R Q Time (min)

DAILY APPLICATION QUESTIONS Involves (a) explanation of observation and (b) applying the concepts to explain how things work around us.

Tips Read the question closely and highlight information in the abstract For application questions, pupils are usually required to make use of the explanation/ observation or answer from an earlier part (E.g: part (a)) May require a combination of Answering techniques

Ken conducted an experiment as shown below to find out how the amount of light reflected by three materials, A, B and C is affected by the distance the material is away from the light source. He set up his experiment as shown in the diagram below. He placed the materials at different distances away from the light source and he used a light sensor to record the amount of light that was reflected. He recorded the results and plotted the results in the graph below. a) Based on the results of his experiment, what can you conclude about the three materials?

From the furthest distance away from the light source, Material C reflects the most amount of light while material A does not reflect any light at all and material B reflects more light than A but less than C.

b) Based on your answer in part (a), which material would be the least suitable for making safety vests for motorists who travel at night. Explain your answer. C: Material A. I: From the graph, the material did not reflect any light when it is the furthest away from the light source. C: Hence, it is the poorest reflector of light. A: It is the least suitable for making vests for motorists as it will not reflect light from a far distance and on-coming vehicles will not be able to see the motorists who travel at night.