Reference

This section of the Learner's Book covers some of the new scientific enquiry skills for this stage. They build on the skills already gained from previous stages. You should refer to these skills whenever you need them.
Measuring the volume of a liquid
Measuring cylinders come in different sizes. Choose one that is the right size for the volume of liquid you want to measure.
Put the measuring cylinder on a table.
Count the lines between two numbers.
On some measuring cylinders each line is 1 ml. On others it can be 2 ml or even 5 ml.
Put your eye level with the top of the liquid to read the scale.
The top of the liquid may curve. Measure to the bottom of the curve. This measuring cylinder contains 43 ml of liquid.

Choosing a bar chart or a line graph

Use a bar chart when your results are different objects or different groups with a number for each one. The bars are separate because each bar shows a different object or group, for example, type of fruit.

seeds	Fruit
5	Apple
10	Orange
30	Kiwi

Brightness at 10 cm	Light source
80 lux	Torch
300 lux	Lamp
20 lux	Candle

Use line graphs when your results are pairs of numbers.
Line graphs can be used to show how something changes with time such as an increase in temperature or plant height.
Here hot water is cooling.

6	4	2	0	Time in minutes
20	25	35	60	Temperature of water in

How to draw a line graph

Eva is measuring the length of a shadow at different times.

These are her results.

14.00	13.00	12.00	11.00	10.00	Time in hours
85	50	25	45	90	Length of shadow in cm

Eva wants to draw a line graph.
First she has to draw the axes.
She looks at the longest shadow length (90 cm). She draws the y axis up to 100 cm.
There are 5 different times to go on the x axis. The times are all 1 hour apart. She draws a line for the x axis.

Eva uses a ruler to draw straight lines.
She writes the numbers so that the lines on the graph paper go through the middle of the numbers.

Now Eva needs to plot the results on the graph.
The first result is 90 cm at 10.00 She finds the line on the graph for 10.00.
She finds the line on the graph for 90 cm.
She makes a cross where the two lines meet.

Next Eva finds the line on the graph for 11.00 and the line for 45 cm.
She draws a cross where the two lines meet.

She plots all the results the same way.
Then she draws a line that goes through the crosses on the graph.

The graph shows that the shadow gets shorter until 12.00. After that it gets longer.

Repeating measurements to make results more reliable

Song and Mansi have a question: 'Will a paper towel that is twice as wet take twice as long to dry?'
Mansi puts five drops of water onto one paper towel. Song puts ten drops on another.
They put both the paper towels on a radiator. They use a stopwatch to time how long they take to dry.

A reliable result is a result that is close to the true answer.
They decide to repeat their measurements.

10	5	Number of drops
15	13	1 Time to dry in minutes
20	12	2 Time to dry in minutes

Mansi's two measurements are similar. Song's are not. To find out which of his results is the most reliable he can repeat the measurement again.

Repeating measurements to check for mistakes

Akiko and Sasha are investigating the question: 'Does the shape of a container affect how fast water evaporates?'
They have 500 ml of water in each container. They measure how much water is left in each container every day.
Here are their results.

5	4	3	2	1	Day
490	493	495	496	498	Water left in measuring cylinder in ml
250	311	445	408	452	Water left in measuring jug in ml

Look carefully at the results.
The water is evaporating so the numbers should be getting smaller.

They decide to repeat the measurements to check.
 

5	4	3	2	1	Day
253	310	345	410	454	Water left in measuring jug in ml

The new results look correct.
The measurement of 445 ml on day 3 was wrong.