krit.club logo

Scientific Enquiry - Ideas and evidence in science

Grade 4Cambridge (IGCSE)

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

•

Scientific ideas are based on evidence gathered through observation and testing. For example, observing the state of H2OH_2O at different temperatures.

•

A prediction is a statement about what might happen in the future based on scientific knowledge. It is often phrased as: 'If I increase xx, then yy will happen.'

•

Evidence consists of measurements or observations that scientists use to check if their ideas are correct. This might include measuring length in cmcm or mass in gg.

•

A 'Fair Test' is an experiment where only one variable is changed, while all others are kept the same (constantconstant) to ensure the results are reliable.

•

Scientists communicate their findings using tables, charts, and graphs to show patterns in the evidence collected.

•

Scientific ideas can change over time if new evidence is discovered that contradicts the old ideas.

📐Formulae

Average=Sum of all measurementsTotal number of measurements\text{Average} = \frac{\text{Sum of all measurements}}{\text{Total number of measurements}}

ΔValue=Final Measurement−Initial Measurement\Delta \text{Value} = \text{Final Measurement} - \text{Initial Measurement}

Distance=Speed×Time\text{Distance} = \text{Speed} \times \text{Time}

💡Examples

Problem 1:

A student wants to test the idea that 'The more water a plant receives, the taller it will grow.' They give Plant A 50 ml50\text{ ml} of water and Plant B 100 ml100\text{ ml} of water daily. Identify the independent variable and the evidence to be collected.

Solution:

Independent Variable: Amount of water (VwaterV_{\text{water}}). Evidence: The height of the plants (hh) measured in cmcm.

Explanation:

In scientific enquiry, the independent variable is the thing you change to see its effect. The evidence is the measurement you take to test your prediction.

Problem 2:

A scientist measures the temperature of a liquid. The initial temperature is T1=22∘CT_1 = 22^\circ\text{C}. After adding a chemical, the temperature rises to T2=35∘CT_2 = 35^\circ\text{C}. Calculate the change in temperature (ΔT\Delta T).

Solution:

ΔT=35∘C−22∘C=13∘C\Delta T = 35^\circ\text{C} - 22^\circ\text{C} = 13^\circ\text{C}

Explanation:

The change in value (Δ\Delta) is found by subtracting the starting value from the final value to provide numerical evidence of the reaction.

Problem 3:

Explain why a scientist repeats an experiment three times and calculates an average.

Solution:

Average=Trial1+Trial2+Trial33\text{Average} = \frac{\text{Trial}_1 + \text{Trial}_2 + \text{Trial}_3}{3}

Explanation:

Repeating tests provides more reliable evidence. Calculating an average helps to reduce the impact of small measurement errors or 'outliers'.