Static electricity investigation

Static electricity investigation

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Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Working with Students
Further Resources
This task is about critiqing the method used in an investigation.

Sandra did an experiment with static electricity. She ran a comb through her hair ten times and then held it over a pile of small pieces of paper.
She counted the number of pieces the comb picked up. She repeated the experiment three times.
Her results were:
 
Trial Number of pieces of paper picked up
1 3
2 7
3 5
 

Question

a)  She noticed her results varied quite a bit.
    To make her experiment as fair as possible what is the best thing for her to do next?

    • Take another reading and see which of the three trials it is nearest.

    • Repeat the experiment with another comb.

    • Choose the highest reading.

    • Do the experiment several more times and average the readings.

    • Calculate the average of the three readings.

Question

b)  Which of the following factors is most likely to increase the fairness of Sandra's test?

    • Possible changes in atmospheric conditions

    • Static electricity building up throughout the experiment

    • Sandra's decision to comb her hair a set number of times before each trial

    • Changing the distance Sandra held the comb above the paper

    •  Varying the shape of the pile of paper

Task administration: 
This task can be completed with pencil and paper or online with auto-marking.
Level:
5
Curriculum info: 
Science, Investigating in science, Physical World
Keywords: 
physical inquiry, energy, electricity, static electricity, fair testing, experimental design
Description of task: 
Students answer two multiple choice questions about fair testing in the context of static electricity.
Curriculum Links: 
Science capabilities
The capabilities focus is brought about by the conversations you have and the questions you ask.
 
Capability: Critique evidence
This resource provides opportunities to discuss the validity of the data collected using this investigative method.
Science capabilities: 
Critique evidence
Answers/responses: 
 

Y10 (09/1997)
a)  Do the experiment several more times and average the readings. moderate
b) Sandra's decision to comb her hair a set number of times before each trial moderate
Diagnostic and formative information: 
  Common errors
a) Option E was chosen by 25% of the students.
b) Option B was chosen by 26% of the students.