How would increasing the pressure of a system will have what effect on the equilibrium of this reversible reaction 3H2 + N2 <---> 2NH3?

Firstly, I would ask the student what they understand about Le Chateliers Principle. "If a system is at equilibrium and a change is made to the conditions, then the system responds to counteract the change", then go on to the explain it to them. I would explain that since its talking about pressure, it affects reactions involving gases and moles.  On the right-hand side, there are 2 moles of ammonia and on the left-hand side one mole of nitrogen and 3 moles of hydrogen. So in total, on the right-hand side there are 2 moles and on the left-hand side, there are 4 moles in total. So if we increase the pressure of a reversible reaction at equilibrium, the position of the equilibrium moves to the side with the fewer number of moles. So if we increase the pressure in this reaction, the equilibrium will move to the right-hand side as there are fewer moles on the right compared to the left. 

I would then ask them another similar question regarding pressure and a reversible reaction to ensure they fully understood what I explained.