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Scientific Enquiry - Drawing conclusions and evaluating experimental results

Grade 5IGCSE

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

🔑Concepts

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Drawing a Conclusion: A conclusion is a statement that summarizes the relationship between the independent variable and the dependent variable based on the data. For example, 'As the temperature (TT) increases, the rate of reaction (rr) also increases.'

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Evidence-based Reasoning: Conclusions must always be supported by the data collected. Scientists compare their final results to their initial hypothesis to see if it was supported or disproved.

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Identifying Patterns: Look for trends in graphs or tables. If a line on a graph goes up, there is a positive correlation (y∝xy \propto x).

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Anomalous Results: These are 'odd' results that do not fit the pattern of the rest of the data. They can be caused by measurement errors or changes in control variables.

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Evaluating Reliability: To make results more reliable, an experiment should be repeated at least 33 times. If the results are similar each time, the data is considered consistent.

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Fair Testing: An evaluation involves checking if all control variables were kept constant. If a variable like volume (VV) or time (tt) changed unexpectedly, the test might not be fair.

📐Formulae

Mean (Average)=Sum of all resultsNumber of trials\text{Mean (Average)} = \frac{\text{Sum of all results}}{\text{Number of trials}}

Range=Maximum Value−Minimum Value\text{Range} = \text{Maximum Value} - \text{Minimum Value}

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

💡Examples

Problem 1:

A student measures the growth of three plants over 77 days. Plant A grows 55 cmcm, Plant B grows 1212 cmcm, and Plant C grows 66 cmcm. Plant B was placed in a warmer room than the others. Calculate the mean growth of the plants in the 'cool' group and evaluate if the test was fair.

Solution:

Mean growth for 'cool' group = 5 cm+6 cm2=5.5 cm\frac{5\text{ }cm + 6\text{ }cm}{2} = 5.5\text{ }cm. The test was not fair.

Explanation:

The test was not fair because the temperature (TT) was not a controlled variable; Plant B was in a different environment, which likely caused the difference in growth (1212 cmcm vs ≈5.5\approx 5.5 cmcm).

Problem 2:

In an experiment measuring how long a candle burns under different sized jars, a student records times of 1010 ss, 1212 ss, and 4545 ss for a 500500 mlml jar. Identify the anomaly and explain how to handle it.

Solution:

The anomaly is 4545 ss. It should be excluded from the average calculation.

Explanation:

The value 4545 ss is much higher than the other two results (1010 ss and 1212 ss), suggesting an error. To improve the evaluation, the student should repeat that specific trial to get a more accurate result.

Drawing conclusions and evaluating experimental results Revision - Grade 5 Science IGCSE