What effect did spacing of exemplars have on concept learning in this study? How did these results compare with subjects’ predictions of their learning?

Article: https://www.gwern.net/docs/spacedrepetition/2008-kornell.pdf

1. How was inductive reasoning involved in the concept learning examined in this study?

2. What effect did spacing of exemplars have on concept learning in this study? How did these results compare with subjects’ predictions of their learning?

3. Why did the researchers conduct Experiment 2? What possible confound did it allow them to rule out?

4. What was your main takeaway from this experiment? If you were going to describe it to someone in a sentence or two, what would you say this research shows?