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Scientific Enquiry - Planning Investigations

Grade 6IGCSE

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

🔑Concepts

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Identifying the Independent Variable: The factor that is deliberately changed in an investigation to observe its effect.

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Identifying the Dependent Variable: The factor that is measured or observed as a result of changing the independent variable.

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Defining Control Variables: The factors that must be kept constant to ensure a 'fair test'. For example, if testing plant growth, the amount of H2OH_{2}O must be the same for all plants.

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Formulating a Hypothesis: A scientific prediction often written in an 'If... then...' format. Example: If the temperature of the solvent increases, then the solubility of the solute will increase.

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Ensuring Reliability: Repeating measurements multiple times and calculating a mean (average) to reduce the effect of random errors.

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Selecting appropriate Equipment: Choosing tools with the correct precision, such as using a measuring cylinder for volume in cm3cm^3 rather than a beaker for more accurate results.

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Safety and Risk Assessment: Identifying potential hazards (e.g., using a Bunsen burner) and stating precautions (e.g., wearing safety goggles).

📐Formulae

Mean (Average)=Sum of all resultsTotal number of trials\text{Mean (Average)} = \frac{\text{Sum of all results}}{\text{Total number of trials}}

Density(ρ)=Mass (m)Volume (V)\text{Density} (\rho) = \frac{\text{Mass } (m)}{\text{Volume } (V)}

Volume of a regular solid=L×W×H\text{Volume of a regular solid} = L \times W \times H

💡Examples

Problem 1:

A student wants to investigate how the temperature of water affects the time it takes for 5g5g of sugar to dissolve. Identify the Independent, Dependent, and two Control variables.

Solution:

Independent Variable: Temperature of the water (∘C^{\circ}C). Dependent Variable: Time taken to dissolve (ss). Control Variables: 1. Mass of sugar (5g5g). 2. Volume of water (cm3cm^3).

Explanation:

To make the test fair, only the temperature should change. Everything else that could affect the rate of dissolving must remain constant.

Problem 2:

During an investigation, a student records the following three values for the distance a toy car travels: 1.2m1.2m, 1.4m1.4m, and 1.3m1.3m. Calculate the mean distance.

Solution:

Mean=1.2m+1.4m+1.3m3=1.3m\text{Mean} = \frac{1.2m + 1.4m + 1.3m}{3} = 1.3m

Explanation:

Calculating the mean from repeated trials improves the reliability of the investigation's findings by minimizing the impact of outliers.

Planning Investigations - Revision Notes & Key Formulas | IGCSE Grade 6 Science