Best App to Learn Tactics?

Hi everyone,

My daughter (8) has recently begun showing interest in chess. While teaching her, my interest in improving has been sparked. I've been downloading a number of apps to practice my tactics, but have been running into a problem. If I'm working out a "make the best move" puzzle and fail, I can usually figure out why the given solution was the best move, but not always. Sometimes the "best" solution baffles me. So what I've been looking for is an app or website that doesn't just provide training puzzles, but also gives explanations with the solutions. I feel like I'm not going to get any better without truly understanding solutions to puzzles. For reference, my ELO seems to hover at about 1300.