The school my son used to attend wanted to be hi tech (I guess) and gave all kids iPads with all textbooks and assignments provided this way. You don't need a study or aversion to technology to realize how bad they are for this purpose. The screen is small, constrained and low fidelity compared to a paper text book. It also (by default, as provisioned) turns off every ~5s to save battery life which is incredibly annoying. It is just objectively worse than paper.