Students hear words presented twice either back to back (massed) or separated by other items (distributed), then attempt free recall. Class results typically show better recall for distributed items, illustrating the spacing effect and motivating distributed study habits.

1. Prepare a list with two occurrences of each target word; arrange half as massed pairs and half as distributed with several intervening items. Include a few buffer words at the beginning to minimize primacy effects.
2. Explain the task: you will read words aloud and most will occur twice; students should remember as many as possible.
3. Present the list at a steady pace (for example, one word every few seconds) until all items are read.
4. Immediately impose a brief distractor task such as counting backward by threes to reduce recency effects.
5. Give the recall signal and allow a fixed time window for free recall; students write down as many words as they can in any order.
6. Reveal which words were massed versus distributed and have students score their own protocols, tallying recall for each type.
7. Aggregate class totals for massed and distributed items and compare recall percentages; discuss the observed spacing effect.
8. Optionally administer a short content quiz before or after the activity to assess understanding of spacing, primacy, recency, and basic experimental design.

📄 Encouraging Distributed Study: A Classroom Experiment on the Spacing Effect - William R. Balch: https://gwern.net/doc/psychology/spaced-repetition/2006-balch.pdf

• Use sentences or short textbook passages instead of single words, spacing repetitions across the list.
• Space practice across sessions or days to demonstrate longer term benefits and include a delayed retention test.
• Compare practice schedules by assigning groups to massed practice blocks versus spaced blocks on real course content.
• Replace auditory presentation with on-screen slides or cards and randomize orders across small groups.

• Ensure timing and scoring are conducted calmly to avoid stress.
• Protect anonymity when discussing individual results in class.

• What is the independent variable in this experiment? (Spacing condition: massed vs distributed.)
• What is the dependent variable? (Number or percentage of items correctly recalled.)
• Why include buffer items at the start of the list? (To control primacy so early items do not inflate recall.)
• Why add a brief distractor task before recall? (To reduce recency so the last items are not unduly advantaged.)
• How could you apply the spacing effect to your studying this term? (Plan shorter, repeated study sessions over time rather than cramming.)
• If your class did not show a spacing advantage, what might explain it? (Insufficient spacing, timing differences, list difficulty, scoring errors, or ceiling/floor effects.)