Every coach feels this tension. Make a drill easy enough that kids succeed, or hard enough that they are stretched? Motor learning researchers Mark Guadagnoli and Tim Lee gave us a useful way to think about it in 2004. They called it the Challenge Point Framework.
You may have heard it sold as “the 70% rule.” That number is not in their paper. More on that below. The idea itself is still one of the most practical tools a volunteer coach can use.
The core idea
Guadagnoli and Lee argued that learning depends on how much useful information a player gets from each rep. Too easy, and there is little new to learn. Too hard, and there is too much to process, so the player cannot sort out what went wrong. Somewhere in between is a “challenge point” where learning is best.
The key part: that point moves. It depends on the player's skill and on how hard the task is for that player. The same drill can be perfect for one kid and useless for the kid next to them.
What about the 70% rule?
The Challenge Point Framework is a theory paper. It does not give a target success rate. Popular articles sometimes add one (70%, or 85%). The 85% figure comes from a 2019 paper by Wilson and colleagues that modeled how machine learning algorithms learn simple yes/no judgments. It was not a study of kids fielding ground balls.
So here is our honest version. As a coaching rule of thumb, we like drills where players succeed most of the time but not every time. Something like 6 to 8 good reps out of 10 is a reasonable place to aim. Treat that as a starting guess to watch and adjust, not a research finding.
When a drill is too easy
Easy drills feel productive. Everyone is moving and succeeding. Think of fielding soft tosses straight at the chest, or playing catch at a distance where nobody ever misses. There is a place for that, especially for beginners and for warming up. But when an older or more skilled player never misses, they are mostly rehearsing what they can already do.
When a drill is too hard
Now picture a 9-year-old taking hard grounders from a coach standing 30 feet away and booting 8 of 10. That is not a useful challenge. The player cannot tell what to fix, and repeated failure with no way out is discouraging. Kids who feel that way tend to enjoy practice less, and some stop wanting to come. The goal is a stretch, not a beating.
Beginners and experienced players need different settings
The framework predicts that less skilled players learn best with a lower challenge: more predictable reps, simpler tasks, more help. More skilled players need more challenge: more variety, more decisions, less help. For a coach, that means running the same drill at two or three levels at once, rather than one level for the whole team.
How to adjust on the fly
- Fielding. Too easy: hit it a little harder, hit it to the side so they have to move, or add a throw to a base. Too hard: roll it instead of hitting it, slow it down, hit it right at them, or drop the throw.
- Hitting. Too easy: move from tee to soft toss, or mix two tee heights. Too hard: go back to one tee spot, or use a bigger, softer ball.
- Catch and throw. Too easy: back up a few steps or add a race against the clock. Too hard: move closer or take away the clock.
- Change one thing at a time so you can tell what made the difference.
Try this at practice
- Count 10. Pick one drill and quietly count 10 reps for a few players. Most of them clean? Make it a step harder. Most of them misses? Make it a step easier.
- Build a 3-level ladder. For your main fielding drill, set Level 1 (rolled ball), Level 2 (hit ball at them), Level 3 (hit ball to the side, throw to first). Players move up after a set of mostly good reps and move down with no fuss.
- Let players choose. Give older kids two stations, “steady” and “spicy,” and let them pick. It gives them ownership. The research on letting learners choose is mixed (McKay and colleagues, 2023, found the benefit likely exaggerated), so watch the picks and adjust.
- Play “beat your score.” Each player counts clean plays out of 10 and tries to beat their own number next round. Competing with yourself keeps the challenge personal.
- Watch faces. Bored means too easy. Frustrated and quiet means too hard. Focused and a little loud usually means you are close.
Guidelines & sources
- Guadagnoli, M. A., & Lee, T. D. (2004). Challenge Point: A framework for conceptualizing the effects of various practice conditions in motor learning. Journal of Motor Behavior. A theory paper; it does not specify an optimal success rate.
- Hodges, N. J., & Lohse, K. R. (2022). An extended challenge-based framework for practice design in sports coaching. Journal of Sports Sciences. Applies challenge ideas to coaching; still largely conceptual.
- Wilson, R. C., Shenhav, A., Straccia, M., & Cohen, J. D. (2019). The Eighty Five Percent Rule for optimal learning. Nature Communications. A mathematical result for machine learning on simple two-choice tasks; not a youth sport study.
- McKay, B., Bacelar, M. F. B., Parma, J. O., Miller, M. W., & Carter, M. J. (2023). Reporting bias and underpowered designs exaggerated the benefits of self-controlled practice. International Review of Sport and Exercise Psychology. Letting learners choose may help less than once thought.
Note on certainty: The idea that difficulty should match skill level is well accepted in motor learning. The exact best success rate for youth players is not known, and the 6 to 8 out of 10 target here is our coaching rule of thumb, not a research number. Direct tests of the framework in real youth team practices are limited.