Can /sci/ work this out?

No.11517936 ViewReplyOriginalReport
So there are 12 people on an island, and 11 weigh the same. 1 person in the group is slightly heavier OR lighter. There are no scales but there is a seesaw - however this can only be used 3 times. How do you find out which person is the odd one out? And whether they are heavier or lighter?