Here are some of my favorites:
Field Trip by the the folks at Niantic, Inc. - Niantic is the creator of the famed PokemonGo and Ingress apps. Well, they took that brand of genius and poured it into this fascinating app. With location enabled, landmarks in range pop up and give pictures and historical information - fascinating! It would be interesting to take a device on real outings and learn more about the area travelled!

Cardboard Camera - This is a cool way to take 360 panoramic pictures with a smartphone or tablet. The program comes with easy step-by-step directions, making it fun for even our youngest of friends to operate. Then, view it with a VR/Cardboard viewer and away you go!
Google Arts & Culture - explore thousands of images found in some of the world's most famous museums and learn about people that created them & those that curate them.

Fascinating experiences!