My kids at certain age (between 2-4 yo) picked up a lot of Spanish by simply watching youtube videos for 1-2 hours a day (their fav. cartoon at the time Pocoyo

My kids at certain age (between 2-4 yo) picked up a lot of Spanish by simply watching youtube videos for 1-2 hours a day (their fav. cartoon at the time Pocoyo was in Spanish). Compared to my learning efforts it was definitely going much easier for them, especially since it was completely unstructured learning for them, they had to figure out the meaning based just on the visual context. They've also learned a lot of Italian at the same time by simply listening to my wife's family talk between themselves (I listened them too, but my Italian still sucks). Problem is that they also forget most of it very quickly around 5 y/o (I guess it matches the period of infantile amnesia) unless they're exposed to the language regularly. So now they still understand Italian very good, but as they've lost interest in that cartoon they've quickly forgot most of their Spanish vocabulary.