If you can’t see what a thing results in, you can’t learn about the thing. Experiments are cultivations of feedback.
Feedback is key to learning. Experiments are basically just an artificial construct set up explicitly in search of feedback. Natural experiments require feedback mechanisms. You couldn’t ever learn to make delicious cake dough if you never baked the cake to see how it the cake made from the dough turned out.
For conceptual learning or memorization, feedback should be immediate, but not so immediate that it takes away some of the Desired Difficulty in trying to struggle through the problem or perform Retrieval. Looking at the answer too quickly will rob you of the chance to struggle through it, and give you the Cognitive Closure of having “felt” like you knew what it was simply due to the Mere Exposure Effect.