Dart Drop Accuracy, Precision, and Uncertainty
Materials: ★★☆ Available in most school laboratories or specialist stores
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★★☆ Some safety precautions required to perform safely
Categories: Lab Skills and Safety, Measurement and Units
Alternative titles:
Summary
Students drop different darts onto a target from varying heights and by different droppers, then analyze how accuracy (closeness to the center), precision (clustering), and uncertainty (spread/standard deviation) change with those variables.
Procedure
- Tape a printed target to a flat board (wood or particle board) and place it on the floor.
- Select three noticeably different darts; assign one primary dropper and two additional droppers.
- Measure and mark drop heights (e.g., 2 ft, 4 ft, 6 ft) using a tape measure.
- For each trial, drop the specified dart from the specified height the required number of times (e.g., 8 drops), keeping the dart vertical and releasing without push.
- After each drop, mark the hole location on the target (or photograph) so hits from each trial are distinguishable; use a fresh target per trial.
- Record polar coordinates for each hit: radius (distance from center) and angle; organize data in a table for every trial.
- Compute for each trial: average radius (accuracy proxy), standard deviation of radius (uncertainty), and plot average radius with ±1σ error bars.
- Compare conditions by plotting:
- Average radius vs drop height (constant dart and dropper).
- Average radius vs number of drops (constant dart, height, dropper).
- Average radius vs dart type (constant height and dropper).
- Average radius vs dropper (constant dart and height).
- Summarize findings: identify which variables most affected accuracy and precision; note any outliers and likely causes.
Links
📄 Simple and Fun Experiment Demonstrating Accuracy, Precision, and Uncertainty - Charles Baukal: file:///C:/Users/ameier/Downloads/simple-and-fun-experiment-demonstrating-accuracy-precision-and-uncertainty%20(1).pdf
Variations
- Add a short “practice” set before official trials to reduce learning effects, then compare with first official trial.
- Increase the maximum number of drops (e.g., 20) to test how sample size changes standard deviation.
- Use heavier vs lighter darts to test mass effects; repeat under a fan to probe air-current sensitivity.
- Replace the circular target with concentric scoring rings to enable a scoring-based accuracy metric.
- Run outdoors vs indoors to compare environmental effects.
Safety Precautions
- Darts are sharp - no horseplay, keep a clear zone around the drop area.
- Wear closed-toe shoes; never reach over the target while someone is dropping.
- Lift darts straight up from the board to avoid splinters and tip damage.
- Use a sturdy backer (particle board preferred) to protect floors and prevent bounce.
- Step stools or ladders (if used for higher drops) require adult supervision and three-point contact.
Questions to Consider
* What is the difference between accuracy and precision? (Accuracy = closeness to true value/center; precision = tightness of clustering regardless of center.)
- Did increasing the number of drops change your uncertainty? (Often the standard deviation estimate stabilizes with more data; report your trend.)
- How did drop height affect accuracy and precision, and why might that be? (Greater height can increase scatter due to small alignment errors and air currents.)
- Did dart type (mass/shape) matter? (Heavier darts may be less affected by air currents; compare your averages and spreads.)
- Which contributed more to variability—equipment (dart/height) or human factors (dropper)? (Support with your error-bar comparisons.)
- How would you redesign the experiment to reduce confounding variables? (Standardized practice, identical dart sets, randomized trial order, blinding of droppers.)