Project based on game 2048
First of all, it seems like rather nice bones of a 2-dimensional array lab. It does not strike me as being too many things at all.


The interface is cleaner with move(direction), but the internal logic is cleaner divided into methods.  Why not the best of both words?  Provide them with starter code that will utilize private methods:

public void move(direction){
  switch(direction){
    case UP:
       slideUp();
    case DOWN:
       slideDown();
   case LEFT:
       slideLeft();
   case RIGHT:
       slideRight();
  }
}

That is another way, also valid.
It seems excessively finicky to require implementation details down to this level.
Once again, I would provide the interface, but not these sorts of implementation details.  You can provide both ways as suggestions, but leave it up to them.  They may also choose a third option that you have not mentioned.
This fits very nicely if you are providing some sort of GUI starter code, which would justify an implementation detail like this one.