In "learn: the bishop" a valid efficient sequence is not allowed.

In "learn: the bishop" the 4th problem, the valid efficient sequence: Be2-Bd3-Bb1-Bc2-Bb3-Ba4 is not allowed. This might be confusing for the entry-level students the problem is meant to help.

Looks like the stars act like pieces and as such block the bishop. I guess it might be confusing anyway, so maybe it would be helpful to mention the bishop cannot move past stars.

Ahh, right. I should have thought of that. Thanks.