Adafruit has a cool little board called the Gemma. It is gerat for wearables because you can use conductive thread to sew right to it. Students have had soe issues getting it going though.
The hardest part is having the Arduino IDE see the board. Adadfruit has a tutorial for this but it is easily missed on the Gemma setup site. Like many things, the fix is simple once you know it. Add this url:
In “Additional Boards Manager URLs” under the Files>Preferences. Then, in board manager (Tools>Boards Manager), you can add Adafruits boards easily.
For a more in depth tutorial, click here