I have 2 daughters aged 7 and 5 and am starting to teach them German. Alongside German lessons, we are using Lingopie. After sampling a few of the cartoons, we watch an episode of 'Coconut the Little Dragon' every day. 'Kokosnuss' is in German with English and German subtitles on the screen.
There are so many features such as clicking on any word and flashcards for each episode but we simply watch the episodes (at 75% speed) and the girls really seem to able to follow the plot (and enjoy it).
I really find that watching something in German every day also helps me with my German but with Lingopie you get 9 languages for the price of 1, so I am also using it to brush up on my Spanish - it's like the Netflix of foreign languages.
There is a free trial so if you are interested, please click on one of the 'Lingopie' images above. Those are my links so if you go through one of those, I get a commission which helps me keep this website free.
Do let me know if you are giving it a try.