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A ruler-drop method records the distance a ruler falls before it is caught. With a suitable conversion table or model, distance can be related to time. The recorded distance itself has units of length; do not label a centimetre measurement as seconds. Use a consistent release position and catching arrangement.
Video by Malmesbury Education. Use the demonstration alongside this lesson’s specification reference and written explanations.
Viewing focus: Define a measurable reaction response
After watching, attempt these questions before opening the answers. You can also use the written lesson below.
After watching 1: What does the ruler initially measure?
A falling distance. Convert with a justified model if time is required.
After watching 2: Why vary or counterbalance condition order?
To reduce confounding with practice or fatigue. Order can affect performance independently of the chosen factor.
What you'll be able to do
A ruler-drop method records the distance a ruler falls before it is caught. With a suitable conversion table or model, distance can be related to time. The recorded distance itself has units of length; do not label a centimetre measurement as seconds. Use a consistent release position and catching arrangement.
Choose one approved factor, such as a controlled distraction condition, and a suitable comparison. Use an unpredictable release without an advance cue that lets the participant anticipate the drop. Do not introduce substances, sleep deprivation or unsafe distractions as required experiments.
Use a consistent practice stage, planned repeats and comparable conditions. A participant may improve through familiarity or change through fatigue, so running every control trial before every treatment trial can confound the factor with order. Counterbalance or randomise order where appropriate.
A within-participant comparison can reduce some between-person differences, but trials on one person are not independent people. Record the participant count and repeats separately, obtain appropriate consent and protect personal results. The centre approves participation and the activity’s suitability.
Retain raw measurements and apply a stated rule for an invalid catch or anomalous result. Compare appropriate summaries and variation. A mean depends on which values are included; silently deleting inconvenient observations makes the result hard to evaluate.
The method includes release, perception, coordination and the catching response, so it is not a direct measurement of one nerve’s conduction speed. A small classroom difference does not diagnose a participant or establish a universal effect. State what was actually compared and identify a useful improvement.
Attempt these problems on paper before opening the worked reasoning. Explain your steps as well as giving a final answer.
Common mistakes to avoid
Key takeaways
Question 1: Three participants each complete five trials. State the numbers of participants and observations.
Three participants and fifteen trials, not fifteen independent participants.
Check the assessed scope and practical or mathematical requirements.
An external explanation or interactive activity to use alongside the lesson. It may include extension material.
Close the notes and answer from memory. Revisit any explanation you cannot yet reconstruct.
Test yourself
Answer a few questions, then review anything you missed.
Start with the quiz above to check the key ideas. You can also choose another topic from the practice library.