1.3 Planning investigations

Summary: Have you ever cooked from a recipe? Did it turn out the way you wanted? The plan for a science investigation or experiment is like a recipe. It lists what equipment and materials you are going to… Tags: science oxford-science student-book-7 Created: 2026-05-19 Last Updated: 2026-05-19

After this topic, you will be able to:

• write a plan for a scientific investigation
• identify the scientific equipment used to measure different quantities
• take accurate measurements.

Think back

1. Name some equipment used to take measurements.
2. What is an independent variable?
3. What is a control variable?

Key idea Scientists first write a plan for their investigation. The plan includes the scientific question, the variables, their prediction, the equipment they need to collect accurate data, a method, and any possible hazards.

Key words plan, method, accurate data, true value, range, interval

Have you ever cooked from a recipe? Did it turn out the way you wanted? The plan for a science investigation or experiment is like a recipe. It lists what equipment and materials you are going to use. It says what you are going to do with them.

Look at the students doing a chemistry experiment in Figure 1.

Figure 1You have to follow a clear plan when carrying out scientific investigations.

Planning a scientific investigation

Figure 2Katie is talking about changing the independent variable in their investigation. Rahim is suggesting how to measure the dependent variable.

In Figure 2, Katie and Rahim want to know whether the temperature of a ball affects how high it bounces. They now need to write a plan for their scientific investigation to find the answer to their question.

A scientific plan includes the following information:

• the scientific question that you want to answer
• the independent and dependent variables
• a list of variables you will control, and how you will do this
• a prediction
• a list of the equipment you will need – this can include a diagram
• a step-by-step method of how you will collect data or make observations
• possible hazards and how to stay safe.

Choosing the right equipment

Your equipment should be able to produce measurements or observations to help you answer your scientific question. For example, you could use a microscope to see very small objects, or a ruler to measure length. You need to choose equipment to measure both the independent and the dependent variables. Table 1 Common scientific equipment. Equipment

Quantity measured

ruler or tape measure

length

thermometer

temperature

stopwatch

time

balance

mass

measuring cylinder

volume

A What equipment should Katie and Rahim use to measure the temperature of the tennis balls?

B What equipment should Katie and Rahim use to measure how high the ball bounces?

You must be able to use equipment correctly to stay safe and collect accurate data. Accurate data is close to the true value of what you are trying to measure. For example, in Figure 3, Rahim needs to look directly at the ruler to get an accurate measurement of the bounce height.

Figure 3Look straight at a scale to take an accurate measurement.

Taking measurements

To answer a scientific question, you often need a number of observations to see a pattern or trend. This means you will need to take several measurements of both the independent and the dependent variables. If possible, you should take each measurement three times.

Katie and Rahim need to choose which temperatures to test for their plan. They need to decide:

• the biggest and smallest temperatures – this is called the range
• how many different temperatures, usually five or more
• the interval (gap) between their temperature measurements.

Stretch zone

1. Copy and complete the sentences. The plan for an investigation includes a list of the blank that you will use. You should name the independent and blank variables, and also any variables you need to blank. You then include a step-by-step blank to explain how you will carry out your investigation.
2. A student decides to investigate how the volume of water in a beaker affects the mass of sugar which can dissolve in it. State which equipment they could use to measure the volume of water.State which equipment they could use to measure the mass of sugar. Describe how to use it.

Stretch zone

1. A student investigates whether the type of surface affects how high a ball bounces. They use four different surfaces. They test each surface two times. Explain why they should read the scale on the ruler by looking straight at it when measuring the bounce height.Suggest why it is a good idea to repeat their results.State and explain whether they need to think about safety for this experiment.