Autumn is edging closer, and the return to a more regular office schedule looms for many people — and with it, the waiting time for transportation, meetings and appointments. Games, reading, social-media scrolls or just zoning out are common ways to spend these spells, but if you want more mental stimulation, why not boost your brain with brief lessons in subjects that interest you? Here’s a guide to finding Android and iOS apps that turn your smartphone into a traveling pocket tutor.

Learn a Language

Web-based academic courses and music lessons have boomed in the past few years, especially as remote learning became a part of pandemic life. Although Apple and Google have their own free translation apps, some people also found online language lessons useful. No one wants to hear you practice your French pronunciation on a commuter train, but several language-instruction apps offer free or inexpensive tutorials in vocabulary and grammar that you can do quietly or while wearing headphones.