Android devices are updated based on schedules dictated by device manufacturers and carriers. Google releases new updates, which can take months to be implemented on devices--if ever. We suggest using the latest manual available even though you may encounter some older devices. The newest manual covers the latest changes in Ok Google, Duo, and Google Now, among other recent changes to the Google and Android ecosystem.
Android Oreo features the Pixel smartphone. Earlier versions feature the Nexus tablet. Manufacturers (HTC, Motorola, LG, etc.) and carriers (Verizon, ATT, etc.) customize their phones and tablets. As instructors, you are likely to run into variations of all kinds in the classroom.
If possible, contact students and remind them to bring a fully charged device and their Google login information.
Students will need access to a Wi-Fi network.