Marble Roller Coaster: Calculations

I have to make a marble roller coaster for my 12th grade physics class and my teacher said that we can choose what we calculate for data. But I have NO idea what i can calculate!

So those of you who have done this, what do you recommend me calculating for my data? acceleration, velocity etc...

Please help!

It would be cool if you could record the velocity of the marble when it reaches the bottom of the roller coaster because it's kinetic energy there will be equal to the potential energy at the top of the roller coaster MINUS losses rolling down. The marble would also have rotational energy so using small marbles would minimize that. You could calculate the rotational energy of the marble if you know it's diameter, density and linear velocity. Or, using a strobe in a dark room, a camera with the lens open and markers on the track to determine how far the marble has moved between flashes, you could calculate the speed of the marble and therefore it's kinetic energy at different heights on the roller coaster to show that the ke+pe at different points and heights sum to the pe at the top of the track.