This question is an interesting one as I would have had a completely different answer 10 years ago. It just goes to show how quickly technology moves on!
Most computers, laptops and mobile devices have inbuilt microphones in them, which are generally quite good, particularly for classroom use. Therefore, I would suggest that if your recording is simply for recording reading, then using the device’s own inbuilt microphone will be perfect.
If for some reason, your device doesn’t have an inbuilt microphone, I’d suggest going to your local Euro shop and buying up a few microphones or headsets. Again, for classroom use, they’re absolutely fine.
Where you’ll need better equipment is if your pupils are starting their own podcasting service or classroom radio station. You can start this off by buying a good quality microphone along with other small pieces of audio recording equipment, all of which you can probably find online for less than €100.
Last Update: March 28, 2018