A graphic display would be best i think,just showing numbers won't be good enough for getting top grades.
I'm in the uk so the provider is actually quite near me 
,sorry i guess i should have fixed my profile a bit better so my location shows,anyway about the blood oxygen sensor could someone tell me if i'll be able to connect both the display and the sensor in one wireless technology for the lilypad(i heard a friend of mine that bluetooth needs one micro-controller per input)so i don't want to buy the sensor and then never use it.