Hypothesis and experimentation

Using several samples reduces the influence of one unusual sample. Understand the benefit of multiple samples.

A chemical spill should be handled safely under trained supervision. Reporting the accident is the correct step.

This statement contains measurable variables such as water amount and plant height. Look for clear variables.

A table makes different measurements easier to read and compare. Identify organised data presentation.

A thermometer is used to measure the temperature of a substance or its surroundings, so temperature is correct. Mass is measured with a balance, time with a clock or stopwatch, and length with a ruler. Exam tip: Learn laboratory instruments by matching each one with the physical quantity it measures.

A successful experiment tests the question fairly rather than merely confirming the hypothesis. Treat fairness as success.

Prior observations and information help form a reasoned hypothesis. Identify the basis of a hypothesis.

Several measurements help identify random variation and allow an average to be calculated. Understand repetition.

Other major conditions should remain the same to test fertiliser fairly. Identify controlled variables.

Broken glass can cause injury and should be removed with trained assistance. Choose the safe procedure.

A conclusion states whether the data support the hypothesis. Identify it as the final data-based statement.

An experiment may support a hypothesis but does not make it final truth. Distinguish support from absolute proof.

A graph changes a table of separate values into a visual pattern. It can show whether one variable increases, decreases, remains steady, or changes irregularly as another variable changes. This makes comparisons easier and helps the investigator notice relationships, trends, unusual readings, and possible conclusions. The axes must be labelled with the variables and suitable units so that the graph is interpreted correctly.

Option C is correct because graphs are used to display relationships and trends in experimental data. They are not mainly for decorating a laboratory or counting instruments, and they should never be used to hide a hypothesis or inconvenient result. For example, plotting water amount against plant height may show whether greater watering is associated with growth under the tested conditions.

An unusual result may reflect an error or a real event so it should be investigated. Record data honestly.

If light is being changed the amount of water can be kept constant. Choose fixed factors other than the main variable.

A clear method allows others to repeat the same procedure. Treat clear steps as necessary for reproduction.

A metre scale is suitable for measuring the length or distance of an object. A stopwatch measures time, a thermometer measures temperature, and a measuring cylinder measures the volume of a liquid. Exam tip: Remember each physical quantity along with its measuring instrument.

A measuring cylinder is used to measure the volume of a liquid, so option D is correct. A balance measures mass, a metre scale measures length, and a stopwatch measures time. In experiments, read the liquid meniscus at eye level.

A hypothesis is a possible answer while a conclusion is based on experimental evidence. Distinguish statements made before and after testing.

A hypothesis gives a possible answer and an experiment tests it. Remember this sequence of scientific inquiry.

Controlled variables are kept the same during an experiment. This makes the effect of the independent variable clear.

Usually only one independent variable is changed in a fair experiment. Other relevant factors are kept constant.

Changing several factors together makes the cause of the result unclear. Change only one factor for a fair test.

This statement gives a testable relationship between light and plant height. Such a hypothesis can be tested experimentally.

The if this then that form makes the cause and expected result clear. It helps make a hypothesis testable.