Handcar only supports a handful of methods that perform searches across multiple objective banks.
You can find an Objective, Activity, or Asset by Id even if you do not know the objective bank where it is stored.
http://mc3-demo.mit.edu/handcar/services/learning/objectives/objective%3A1%40MIT-OEIT
http://mc3-demo.mit.edu/handcar/services/learning/activities/activity%3A1%40MIT-OEIT
http://mc3-demo.mit.edu/handcar/services/learning/assets/activity%3A251%40MIT-OEIT