Scientific questions and observations

A centimetre is a unit used to measure length, so it is the correct option. A litre measures volume, a gram measures mass, and a second measures time; none of these is suitable for observing length. Exam tip: First identify the physical quantity being measured, then choose its appropriate unit.

Direct answer: Option C, recording all results using the same rule. Scientific observation must be fair and systematic. First decide the rule for what will be observed and how it will be written; then apply that rule to every result, including results that do not support the expectation. This reduces the observer’s personal preference and makes comparison possible. Option A is wrong because recording only preferred data hides evidence and creates bias. Option B is wrong because unusual data may be important; it should be checked, not secretly removed. Option C is correct because identical rules give every result an equal chance of being recorded. Option D is less suitable because predicting beforehand may create expectation bias; a prediction is not a method for recording observations. Memory cue: fair observation means “same rule, every result.”

Different results may arise from an instrument problem, an inconsistent method, or reading error. Therefore, check the setup and procedure before repeating the measurement.

A question using how does it affect shows a relationship between two variables. Such a question is usually testable.

Change in the plant’s height per week is a numerical, objective measure of growth. It allows a fair comparison between plants given fertiliser and plants not given fertiliser. Leaf colour may indicate plant health, but it is not a direct, precise measure of growth. Exam tip: In an experiment, choose measurements that can be recorded numerically and compared at equal time intervals.

Failure to germinate is an observation but calling the seed dead is a conclusion. Additional evidence is needed for the conclusion.

For an observation of a phenomenon that changes over time, recording the date and time shows when the change occurred and how quickly it happened. This helps identify the sequence of events and a trend. For a one-time observation of a fixed colour, time is usually less important. Exam tip: Record date and time whenever an observation involves change or sequence.

A ruler measures the distance between two points. To measure an object correctly, its starting end should be placed at the ruler's zero mark, while the other end is read on the scale. The ruler should lie straight along the object, and the eye should be directly above the mark to avoid parallax error. These steps make the reading more dependable.

Thus, the zero mark must coincide with the object's starting end, so option B is correct. If the object cannot be placed at zero because the ruler is damaged, another clear mark may be used as a starting reference, and the difference between the two readings is calculated. However, among the given choices, placing zero at the starting end is the standard and simplest method.

The direct answer is C: keep the other factors the same. To study the effect of one factor fairly, that factor is changed deliberately while other relevant conditions are controlled. The changed factor is the independent variable; the result measured is the dependent variable. Step by step: choose the factor to test, change only that factor, keep temperature, amount, time, apparatus, and other relevant conditions constant, then compare the results. Option A is wrong because changing everything makes it impossible to know which factor caused the result. Option B is wrong because ignoring other factors may allow them to affect the result unnoticed. Option C is correct because controlling the other factors makes the test fair and the conclusion clearer. Option D is wrong because guessed conditions are not controlled scientific conditions. For example, to test whether light affects plant growth, keep plant type, soil, water, pot, and time the same while changing light exposure. Exam cue: one variable changed, the important others controlled.

How do plants grow is too broad and lacks clear variables. Narrow it to one measurable factor.

The direct answer is A: daily change in the shape of a seedling. Drawings are especially useful for showing visible form, structure, arrangement, and how these change over time. A labelled drawing made on successive days can show the seedling’s developing stem, leaves, direction of growth, and overall shape. Option A is correct because shape and structure are visual features that a drawing can record directly. Option B, water temperature, is best recorded with a thermometer and a numerical value such as degrees Celsius; a drawing would not give a reliable temperature. Option C, mass, should be measured with a balance and recorded in grams or another suitable unit, not estimated from a picture. Option D, experiment duration, should be recorded using dates, times, or a clock; a drawing does not measure duration. For a useful scientific drawing, include the date, use clear lines, label important parts, and keep the relative form as accurate as possible. Memory cue: draw what you need to see; measure what needs a number.

Data obtained using the same method and unit can be compared properly. Maintain consistency in the procedure.

Measuring the temperature of the same liquid three times is repetition. Repeated measurements help identify unusual or erroneous readings and allow an average to be calculated, making the result more reliable. Bias occurs when a measurement or conclusion is influenced by a prior expectation. Exam tip: repeated measurements taken to improve reliability indicate repetition.

The form of the answer is less important than testability. A question testable with evidence can be scientific.

Option C clearly states the number (“four”), the location (“in the school ground”), and the activity (“pecking grains”). Option B mentions the birds’ condition, but it does not give their number or location. Exam tip: In a scientific observation, note how many organisms were seen, where they were seen, and what they were doing.

An initial observation involves noticing an event, pattern, change, or problem carefully. It generates curiosity and helps frame a scientific question that can be investigated. Option A is incorrect because an observation does not decide the answer; it only provides a direction for investigation. Exam tip: A scientific question is often linked to an observed event and asks what, how, or why.

A plant bending towards a window is an example of phototropism. Therefore, the testable scientific question is whether the direction of light affects the direction in which the plant bends. The colour of the pot or wall is not directly linked to this observation. Exam tip: A scientific question should include factors that can be changed and measured.

Stating the duration shows how long data will be collected and the time period to which the conclusion applies. Therefore, option D is correct. Specifying a duration does not predetermine the result or remove the need for instruments. Exam tip: Include the time period, place, and variables in an investigation question to define its scope clearly.

Direct answer: Option B, an observation can generate a question and the question guides further observation. Science often begins when someone notices a pattern, difference, or surprising event. That observation creates curiosity and leads to a question that can be investigated. The question then helps decide what to observe next, what evidence to collect, which variables matter, and how to design a fair test. Step by step: observe something; notice a possible problem or pattern; ask a clear question; collect relevant further observations or measurements; use the evidence to build and test an explanation. Option B is correct because observation and questioning support each other in an ongoing investigation. Option A is wrong because they are closely connected. Option C is wrong because a scientific question normally comes before a conclusion, not only after it. Option D is wrong because observations require evidence; without evidence, a statement is merely an unsupported opinion. Memory cue: observe, ask, investigate, conclude.

The leaf colour is a fact directly noticed through the senses. Treat directly obtained information as an observation.

A quantitative observation uses numbers and units. Look for measurements such as length mass or time.

Water temperature is the factor deliberately changed. Identify the variable changed as the cause.

Height is measured using numbers and units so it is quantitative data. Identify measurement-based data in exams.

Fertiliser amount and plant height are two measurable variables. Identify questions asking about an effect or relationship.

Roughness is a quality noticed through touch and has no number. Treat sense-based descriptions as qualitative.