Students rapidly open and close a spring clothes peg in three 30-second bouts to observe muscle fatigue and recovery. Results are graphed to link falling repetitions with the switch from aerobic to anaerobic respiration and lactic acid buildup.

1. Gather materials per pair: 1 spring clothes peg (same type for all pairs), stopwatch or timer, data sheet, pencil, and optional alcohol wipes for shared pegs.
2. Standardize the setup: use the same peg model and spring strength for all students; hold the peg between thumb and forefinger of the writing hand unless testing hand differences.
3. Practice for 5–10 s to learn the full open–close motion. The peg must open fully each count; partial opens do not count.
4. Assign roles: Performer (squeezes and counts aloud) and Timekeeper (calls time marks and records counts). You will swap roles after the first run.
5. Run 1 (writing hand): on “go,” perform as many full opens as possible in 30 s. Timekeeper records the total for 0–30 s.
6. Rest exactly 15–30 s (use the same rest for everyone).
7. Continue immediately for the next two intervals without resetting the count aloud. Timekeeper records the additional opens achieved during 30–60 s, then during 60–90 s (counts per interval, not cumulative).
8. Swap roles and repeat Run 1 with the partner following the same timing and rest.
9. Optional Run 2 (non-writing hand): repeat the three 30 s intervals to compare hands.
10. Graph results for each person: x-axis = interval (0–30 s, 30–60 s, 60–90 s); y-axis = opens per 30 s interval. Plot both partners on the same axes for comparison.
11. Analyze briefly: note where performance drops, describe sensations (burning, slowing), and connect to energy use (aerobic early, increasing anaerobic contribution later). Record one or two sentences interpreting the pattern.

📄 ACTIVITY: Finger marathon - Science Learning Hub: https://www.sciencelearn.org.nz/resources/1926-finger-marathon

• Recovery test: repeat the 3 × 30 s set after rests of 1 min, 3 min, and 5 min to estimate recovery time to first-interval performance.
• Dominant vs nondominant hand: run both hands; compare interval shapes and totals.
• Peg tension: compare light vs heavy-spring pegs (measured with a simple force gauge or labeled by the manufacturer).
• Fitness or musician subgroup: compare class averages for students who self-identify as athletes or instrumentalists with others.
• Class statistics: compute means and ranges for each interval; add error bars to graphs.

• Avoid pinching skin; use intact, smooth pegs only and replace damaged ones.
• Stop immediately if pain, cramping, or numbness occurs; shake out the hand and rest.
• Limit total sets to prevent overuse; alternate hands if doing multiple trials.
• Clean shared pegs or hands between users to reduce germ transmission.

• Why do counts usually decrease across intervals? (Oxygen delivery cannot keep pace with demand; anaerobic pathways contribute more, yielding less ATP per glucose.)
• What causes the burning sensation? (Accumulation of lactic acid and related metabolites interfering with contraction.)
• Which fiber types are recruited as the task continues? (Slow-twitch dominate early under aerobic conditions; fast-twitch are recruited as intensity and fatigue increase.)
• How does rest restore performance? (Oxygen replenishes, lactate is cleared, and phosphocreatine stores are rebuilt.)
• What controls make this a fair test? (Same peg type, timing, instructions, and rest; only the intended variable changes.)