Order of inserting dimensions?

I am a brand new user of Sketch Up. I have watched the introduction to Sketch up videos. What I can’t seem to find is the order in which dimensions for an object are given. For example, I need to create a rectangle that is 2 feet by 4 feet. Which number do I enter first? It seems that whatever I do, the wrong shape occurs and is not oriented in the way I want it to appear. Is there a convention that indicates you enter the length dimension, followed by the width dimension, or the other way around? Or do you just go with what appears and rotate it into your desired view and orientation?

Dimensions are usually entered in the order r,g,b, although there are exceptions. But you can make it easy on yourself. Next time you drag a rectangle, keep an eye on the dimensions rolling in the Measurement toolbar. When your rectangle is oriented correctly on the screen, note whether the dimensions appear as “big, little” or “little, big”. Then you can enter the actual dimensions in the same order.

I’m a big believer in constructing objects off to the side and moving them into position after, but it’s still reasonable that you would have a preferred orientation even when you work on the object in isolation. So yours is a perfectly reasonable question.