Some basic articles - good for new photographers (covers some basic rules of photography, so maybe for the kids)
https://iphonephotographyschool.com/...tography-tips/
http://www.digital-photography-tips....otography.html
https://digital-photography-school.c...-camera-phone/
More relatively basic info but with a few great photos!
https://www.nationalgeographic.com/p...-phone-photos/
https://blog.hubspot.com/marketing/g...res-phone-tips
Now we step up a bit in complexity / quality of tips.
https://iso.500px.com/35-mobile-phot...rtphone-shots/
https://www.pixelz.com/blog/use-smar...roduct-images/