Required practical 7: reaction time and fair comparison
| English | 中文 | Pinyin |
|---|---|---|
| anticipation/ænˈtɪsɪpeɪʃn/ | 预期 | yù qī |
| reaction time/rɪˈækʃn taɪm/ | 反应时间 | fǎn yìng shí jiān |
What would explain this observation?
- A ruler-drop result can improve because someone learns when to expect the drop. A fair investigation must distinguish the chosen factor from practice and anticipation 预期.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- Reaction time 反应时间 is the interval between a stimulus and a response. In required practical 7 a suitable factor is investigated under school supervision. A ruler-drop method measures the distance fallen before a catch. Use a supplied conversion chart if time is required; distance in centimetres is not automatically time in seconds.
- reaction time: The interval from a stimulus to the response; anticipation: Responding based on an expected cue before the actual stimulus.
Why should the releaser avoid giving a countdown?
The chosen factor must change while other relevant conditions stay comparable. Keep the starting ruler position, hand position, catching method and instructions consistent. Avoid advance cues to the release. Repeated trials reduce the influence of random variation; a planned order can reduce practice or fatigue effects. A shorter drop distance generally indicates a quicker catch in the same method.
Match each technical term to its precise meaning.
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- The chosen factor must change while other relevant conditions stay comparable. Keep the starting ruler position, hand position, catching method and instructions consistent. Avoid advance cues to the release. Repeated trials reduce the influence of random variation; a planned order can reduce practice or fatigue effects. A shorter drop distance generally indicates a quicker catch in the same method.
- Use informed, voluntary participation and an alternative supplied-data task. Choose a low-risk factor such as a stated distraction under teacher guidance, not sleep deprivation, stimulants, illness, distress or strenuous exertion. Repeat enough trials, record all results and use a mean or justified treatment of an anomalous result. Do not rank students’ ability or infer medical conditions.
Which two habits make the investigation or model in this case more defensible?
Use informed, voluntary participation and an alternative supplied-data task. Choose a low-risk factor such as a stated distraction under teacher guidance, not sleep deprivation, stimulants, illness, distress or strenuous exertion. Repeat enough trials, record all results and use a mean or justified treatment of an anomalous result. Do not rank students’ ability or infer medical conditions.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: model catch distances are 18, 22, 20, 19 and 21 cm. Mean = 100/5 = 20 cm. A second condition averaging 25 cm suggests slower catching under the same method. Without repeats, order control and comparable starting positions, the difference cannot confidently be assigned to the chosen factor.
Model catch distances are 16, 20, 18 and 22 cm. Calculate the mean. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
Model catch distances are 16, 20, 18 and 22 cm. Calculate the mean.
The result is 19 cm. Known: model catch distances are 18, 22, 20, 19 and 21 cm. Mean = 100/5 = 20 cm. A second condition averaging 25 cm suggests slower catching under the same method. Without repeats, order control and comparable starting positions, the difference cannot confidently be assigned to the chosen factor.
Check the conclusion and its limits
- A result is a measurement under particular conditions, not a permanent personal characteristic. Never silently discard the largest value just to improve the mean. A distance-to-time conversion must use the specified model or table rather than relabelling centimetres as milliseconds.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
A ruler distance in centimetres is numerically the same as reaction time in seconds. This claim is false: A result is a measurement under particular conditions, not a permanent personal characteristic. Never silently discard the largest value just to improve the mean. A distance-to-time conversion must use the specified model or table rather than relabelling centimetres as milliseconds.
Required practical 7: reaction time and fair comparison: The chosen factor must change while other relevant conditions stay comparable. Keep the starting ruler position, hand position, catching method and instructions consistent. Avoid advance cues to the release. Repeated trials reduce the influence of random variation; a planned order can reduce practice or fatigue effects. A shorter drop distance generally indicates a quicker catch in the same method.
A ruler distance in centimetres is numerically the same as reaction time in seconds.
A result is a measurement under particular conditions, not a permanent personal characteristic. Never silently discard the largest value just to improve the mean. A distance-to-time conversion must use the specified model or table rather than relabelling centimetres as milliseconds.
The interval from a stimulus to the response: write the technical term.
reaction time means The interval from a stimulus to the response.