Android tablets include the Asus FonePad, Google Nexus range, Amazon Kindle Fire, & Samsung Galaxy Note (to name just a few).
There are also cheap android education tablets specifically designed for kids. LearnPad is an one such exclusive tablet. It is promoted as a cost effective simple tablet for primary, secondary and students with Special Educational Needs (SEN). This white paper by LearnPad provides a comprehensive overview of the issues one should consider before deploying tablets within a school.