Can one device do everything?

Sometimes it is cost effective to have more than one device.  

This depends on your specific requirements and often the schools policy towards mobile phones.  

Examples

If it is important to take a photograph of the board, or create reminders......  and a student can use their phone then the device does not need to carry out these functions.

If audio recording is important, consider buying a digital voice recorder. While most phones have voice recording facility, they take up a lot of valuable space.  Once a phone is full it is no longer helpful.

Buying multiple devices is sometimes more cost effective than
buying one high end computer that can do everything.

When phones are used for audio recordings / taking photographs an efficeint workflow is essential to ensures these valuable files are easily transferred to the students device rather than just staying on their phones.

Keep an eye on students to ensure they know where to find all the resoruces produced in lessons. They are only useful if they can be found easily.