A method for classifying motion of a user includes: during a second time interval, receiving a set of sensor signals from a set of motion sensors arranged within a wearable device； from the set of sensor signals, generating a set of quaternions corresponding to instances within the second time interval； generating a set of motion features from the set of quaternions； transforming the set of motion features into a second action performed by the user within the second time interval； and transmitting a flag for the second action to an external computing device in response to a difference between the second action and a first action, the first action determined from data received from the set of motion sensors during a first time interval immediately preceding the second time interval.
