Apps For Chinese Story For Pre School

Hi. I am English Ed. I enrolled my son to a Chinese based kindergarten. I usually buy and read English story books for him. I sometimes try to get those Chinese story book with Hanyu Pinyin. But sometimes there are words that I'm not familiar, afraid if I read it wrongly. I wished to know which apps to download that has nice Chinese story for pre school children. Thank you very much ☺️