Dewey explains that, to have an educative experience, a student must have an anticipatory feeling and be able to immerse themselves in that learning environment. Students that attend class may experience new concepts or ideas through lecture or activity and while they are a part of that body of learning, they aren't necessarily having "an" experience. One can participate in the classroom environment, but if the lesson doesn't allow a real opportunity to begin, develop, and have a meaningful conclusion, the learning aspect is not integrative in a real way that can be used for retention and further development.
Think about it in terms of learning a skill versus having a skillset. When a coach has a group of 5th graders trying out for the basketball team, would it make sense if the athletes were only taught and practiced passing the basketball? No, of course not. Passing is one aspect of the game! The team needs to also learn how to shoot, rebound, dribble, and play defense. If the only skill the coach focuses on is passing, the game would never make sense to players (or fans!). It's in the learning of the entire repertoire of skills that make up the game of basketball, and when those goals are clear, the game makes sense to the player.
A basketball player cannot watch the coach shoot and dribble and learn how to play. Likewise, a player cannot understand the mechanics of a bounce pass or a bank shot perfectly and thus be able to preform the skill. They instead need to learn how their body moves across a court in conjunction with their teammates and opponents, anticipate where a missed shot may come off the hoop so they can be in position to rebound, and feel the ball arch from their fingertips during a free throw. The combination of skills and practice is what provides "an" experience, which can be practiced, honed, and tweaked.