Hypothesis and experimentation

After an experiment the data are analysed and a conclusion is written. State whether the hypothesis was supported.

Height and the seven day period provide clear measurements. Happiness or beauty is difficult to measure objectively.

Safety gloves are useful when handling chemicals or other substances that may cause irritation, injury, or harm to the skin. Therefore, option B is correct. Using a ruler or making a table does not normally involve a skin hazard. Exam tip: remember safety equipment by linking it to the specific hazard it prevents.

The correct answer is that an additional factor also changed. Since the student wanted to test the effect of water amount, all plants should have received the same amount of light. Different light levels can affect plant growth along with water, so the result would not be a fair test. Option B describes the correct experimental condition, but the question states that the light levels were different. Exam tip: when testing one variable, keep all other variables controlled.

When data do not match the expected result the hypothesis is not supported. It may be revised.

First a question is asked and a hypothesis is formed as a possible answer. Then a test is planned.

The direct answer is B: the results may become more representative. A sample is one member or small part selected from a larger group. If an experiment uses only one or two samples, an unusual sample may strongly affect the conclusion. Increasing the number of samples gives more information about the group as a whole and can reduce the influence of unusual individual results. Option A is wrong because more samples usually require more time and materials, so the experiment will not always be shorter. Option B is correct because a larger sample can better represent the general condition of the group, although good selection and identical procedure are still necessary. Option C is wrong because increasing sample number does not remove the independent variable; that variable is the factor deliberately changed. Option D is wrong because units are still needed for measured quantities, whatever the sample number. Use the same method and fair conditions for all samples, and report the sample number. Memory cue: more suitable samples usually mean a stronger picture of the whole group, not automatic perfection.

When an experiment is repeated under the same conditions and gives the same or very similar results, the result is considered more reliable. Therefore, confidence in the result increases. Personal opinion and bias do not strengthen scientific evidence, while vagueness makes a conclusion less clear. Exam tip: Similar results on repetition indicate the repeatability of an experiment.

Direct answer: D, inform the teacher and remove the glass with suitable tools. Broken glass can cut skin and may carry chemicals, so touching it with bare hands is unsafe. Step by step: stop the activity, warn others, keep away from the pieces, tell the teacher, and use approved tools such as tongs, a brush, and a dustpan as instructed. D is correct because it follows safe laboratory practice. A is dangerous because hands may be cut. B leaves a hazard for someone else. C is wrong because ordinary bins may not be suitable for sharp glass. Memory cue: broken glass means report, isolate, and use tools.

Average height is a result based on measured data. Words such as liked and always weaken a scientific conclusion.

A hypothesis gives a testable answer to a question and an experiment gathers evidence. A conclusion is formed from the results.

The time taken to boil is the measured outcome so it is the dependent variable. Identify the measured result.

Container size is deliberately changed so it is the independent variable. Choose the factor changed by the experimenter.

Soil type is being changed so the number of seeds should remain the same. Identify controlled variables.

Direct answer: Option B, checking whether measurements use the same units, should be done before comparison. A number has meaning only with its unit. For example, 2 m and 150 cm are not directly compared as 2 and 150 until one value is converted: 2 m = 200 cm, so 200 cm is greater than 150 cm. First inspect every value and its unit, convert all values to one common unit, and then compare them. Option B is correct because common units prevent a false conclusion. Option A is irrelevant: a hypothesis title does not tell whether numerical data are comparable. Option C is irrelevant because equipment colour does not affect the unit or value. Option D is not the required check; different students may collect useful data if the method and units are consistent. Memory cue: before comparing numbers, compare their units.

Direct answer: C, the number of pulse beats per minute. The hypothesis predicts that exercise changes pulse rate, so pulse rate is the dependent variable: the result that is measured. Step by step: measure the resting pulse, give different or defined amounts of exercise, count beats for one minute, and compare the values. C directly tests the prediction. A is identifying information, not the outcome. B is unrelated to pulse rate. D is also unrelated and cannot show the effect of exercise. The exercise amount is the factor changed, while pulse beats per minute are measured. Memory cue: measure the result named in the hypothesis.

After an experiment the recorded data are analysed and a conclusion is written. Remember the correct sequence of scientific inquiry.

A dependent variable is the outcome that is observed or measured in an experiment. Here, the time taken by seeds to germinate is measured after changing the amount of water, so option C is the dependent variable. The amount of water is the independent variable, while the type of seed may be kept constant as a controlled variable. Exam tip: identify what is changed as the independent variable and what is measured as the dependent variable.

A list of instruments helps conduct the experiment systematically. Check all required materials before starting.

A hypothesis may be revised when repeated evidence goes against it. Revision should be based on data.

The plant that receives no fertiliser is kept under normal conditions so that the growth of the fertilised plant can be compared with it. Therefore, it is the control group. Applying fertiliser is the independent variable, while plant growth may be the dependent variable. Exam tip: The group that does not receive the factor being tested is the control group.

An experimental procedure is the clear, ordered description of everything done in an investigation. It should state the materials, the steps, the conditions kept the same and the way observations or measurements are recorded. A clear procedure allows another person to understand what was done and repeat the investigation fairly. Repetition is important because it helps check whether a result is dependable and whether a conclusion is supported by evidence.

Option A is correct because an unclear procedure may prevent another person from repeating the experiment correctly. Option B is not guaranteed: a dependent variable may increase, decrease or remain unchanged. Option C is an unsupported claim; instruments do not automatically break merely because instructions are unclear. Option D is also false, since an unclear procedure cannot prove a hypothesis immediately. Clear, ordered steps improve reliability and communication.

In option A, the duration for which fruits are kept in sunlight is the independent variable, while the change in fruit mass is measured as the outcome. Therefore, mass is the dependent variable because it may change with the duration of exposure. In option B, mass is deliberately varied, so it is an independent variable. Exam tip: The quantity measured or observed as the result is usually the dependent variable.

Measurements in the same units can be compared correctly. Convert different units to a common unit first.

The first statement is limited to the collected data. Avoid words such as always or certainly without sufficient evidence.