What's the maximum amount of electrical outlets that can be connected in parallel using a 15 Amp or 20 Amp breaker? I'm supposed to search this for an assignment, but I can't seem to find one straight answer...

The answer depends on your location.

In the US under the NEC you can look for 220.14(I)

I am not an electrician but I do not think there is a limit on how many receptacles can be installed. Building and electric codes will say how far apart they can be and how many in a room but won't limit the number.

What is this assignment for? This is pretty easy stuff in the electrical world, didn't they give you a study manual or course guides?

I believe that the breaker should protect the wire size in a circuit. You can have 20 oulets on a circuit, but at the end of the day the breaker must protect the wire. Where I come from anyway..

Cvander, Please refer to the Code that allows twenty outlets on any circuit.

Superst, Stan gave you some direction, assuming your located in the USA, and assuming non-residential situation, and can be used for residential.