I don't know if the datasheet for the MC68HC11A8 is part of your course material. If not, it would be very useful to you, and you can get it
here.
The base device, the 6800, didn't have the addressing modes you have in this device. The direct mode is relatively limited; the extended mode is akin to what better micros of the time referred to as direct mode.
This device also borrowed the indexed addressing modes from the Z-80. It's the indexed modes that caused me to comment on the index+offset mode. While the addition of the two values is important, the sizes are different between the two portions. One part may be fixed in the instruction in some chips.
In the Z-80 the offset was fixed; only the index register could be incremented. That made it somewhat limited. If one were walking memory, one lost the base while incrementing the index register, thus requiring the base to be saved by pushing it onto the stack or storing it somewhere. The same is true in this chip.