I'm trying to re-learn chess with the wonderful Chesscademy site.
This exercise asks me to "make a move that will leave you up two points in total".
As the hint suggests, I've counted up the number of points on the board - I make it 38 for white, 37 for black. (I'm playing white).
So, clearly white needs to take 1 point of black's material in order to turn the 1 point lead into a 2 point lead.
Moving c4 x f7 - taking one black pawn - is the correct answer according to Chesscademy. But why isn't my initial answer of f3 x e5 - also taking one black pawn - also correct?
(For what it's worth, both moves could subsequently result in the loss of a 3 point white piece in a real game, so it's not due to a difference here.)