BookWidgets - BookWidgets is an excellent application that let you create engaging exercises in minutes and easily share a varied variety of beautiful and fun activities with your classroom and others.
F-Droid - F-Droid is an interesting alternative for Android users who want to try something different and not have to use the Goole Play store all the time.
Padlet - Visual boards for organizing anything.
APK Pure - Download apk for Android with APKPure APK downloader. NoAds, Faster apk downloads and apk file update speed. Best of all, it's free
Quizlet - Quizlet allows you to review and create flashcards for a variety of subjects, such as math and reading.
APKMirror - Android Market and APK Downloads