Here is nice unit for students to work on for the structure of the sea floor and how that is linked to plate tectonics.
I have had student do the seafloor activity with great success. First they build a shoebox model of the seafloor, making sure to include all the features that might be found going out from a continental shelf towards the abyss.
After each group is done with their model they cover it up, (thin black weed barrier cloth works well) and then trade it with another group.
For the second part the task is to measure the depth of an unfamiliar model, draw a contour map and try to identify the structures present.
This really gets them going since they actually have to have pretty good understanding of the features involved to be able to identify them. There has typically been a lot of looking at the examples provided back and forth to try to identify what the are sensing, before the grand moment in the end where the get to take the cover off and see how accurate their model was.