Office Mix is a free add-in for powerpoint. You can download it onto your device directly from the Office Mix website: https://mix.office.com/en-us/Home
You can access a huge range of terrific Office Mix tutorials at https://mix.office.com/gallery/category/how-to
Visit the Microsoft Educator Community to learn more about Mix and complete the course for Workshops 1: https://education.microsoft.com/GetTrained/Office-Mix-for-Teachers-Basics
Check out how Trent Ray has used Mix to engage with his students – I particularly like how he has used the laptop graphic to frame the video – cool.