Hair particle system size?

I’m sure that I am not the first with this question, and I did a quick search, so I apologize for asking this if the solution is obvious.

In 2.79 I am trying to use the hair system to randomly place objects on a plane, but I cannot find the size option for particles in 2.79. Pretty much every tutorial adjusts this option. I don’t see a size option anywhere in 2.79 under the physics section.

Here is a pic