How much ipad time do you think is OK for a preschooler? My boy has learnt a lot about topics that interest him such as dinosaurs through YouTube videos. I'm just thinking whether is it causing more harm than good?

for me I restrict the timing and frequency of ipad usage. If he asks, I don't give him, even if he cries and throw tantrums. He has to learn ipad is not an entitlement. And he gets at most 15min airtime. He usually plays some mini games, some is about numbers, watches some children songs, maybe watch abit of cartoon that's all. I usually only use it as a last resort to make him do what I need him to do, distract him so that I can do my things like eat, etc. I'll try other things first like toys, books etc.