3D is where it's at, stop looking at plans and elevations.

well.. a plan is just a plan, an organizer for your programs and doesn't often translate to what one would experience in reality.  A section is closer to human experience of perspective in reality.  People never experience architecture in plans.. They're always standing, looking forward, moving in 3D space, perspectival space.  The fact that you say, 'In plan, things make more sense to you' is just out of your own convenience.  Also, you need to visit more building.  I think most of us wouldn't be moved when walking into a guy either.  But go visit a gothic cathedral or St. Peters Basilica in Rome and then compare the feeling of a building with high spaces compared to perhaps your dogs kennel in an extreme example :/

many, or most, or all office buildings have a 2 story atrium at the entrance don't they?  go there.  stand in a vestibule and think 'this is not a big space.'  then exit the vestibule and stand in the atruim and think 'this is a bigger space.'  then go to the bathroom and think 'it's small again.'  perhaps that will help?

i think 3d would make more sense, but perhaps your professor hasn't been informed that people can do 3d drawings now.  it also might help to draw a few sections.  take you plan, draw a 6'2" scale figure, and draw what that person looks like in section, then move the ceiling up and down or something.  maybe have a light cove or a border with a shorter perimeter.  put a really tall ceiling in your atrium then hang a chandelier in the middle.  or a big sheetrock circle.  or a ceiling tile grid without ceiling tiles.  then just kind of see what the scale figure looks like.

i was gonna think in section, but i got high                                                                                          was gonna draw with some affection, but i got high                                                                          and now my prof is yellin', and i know why

because i got high, because i got high, because i got high

LA DE DA DA DA da ..

Without an introduction to this kind of thinking through precedent, it is very difficult for the new student to comprehend.

Why don't you go walk through some of your favorite spaces, and draw sections of the spaces you find pleasing? Also include the rooms or spaces outside the one you are inside so you can see how the section changes through the building.

Or draw a section of the ceiling height as you walk through a building in a straight line and see what you come up with. It will almost never be constant along a circulation path.

Miles, 3D is great once you have a concept or parti, but sketching in 2D, including sections, is a crucial part of learning to design.

oh boy. Every cultural institution or enclosed public space is essentially an atrium. Scope is much wider than 'gym at my school'. Your prof is not even trying to get you do design such spaces. He/she is covering the basics, which is to help you start thinking spatially (and you seem to definitively need help with that).

Visualizing in 3D is a vital ability...in your minds eye, not electronically. It seems a lot of those who decide on Architecture have very little experience in experiencing Architecture. When you experience a building, be sure to not just look, but see, and use all your senses. For most, it's an innate ability, but I think it can be nurtured.

Also helpful perhaps: experiencing various sized doors or windows. Have you ever experienced 14 foot high doors? A window that cuts off the view?

i was gonna s'perience space, but i got high                                                                                      was gonna go to my favorite place, but i got high                                                                               and now i can't state my case, and i know why

because i got high, because i got high, because i got high

LA DE DA DA DA da ..

I will disagree with most posters here. "Thinking in 3d" should come from experiencing spaces, and not with the help of 3d software. Sure, 3d software is a great help, but I think the OP is having problem visualizing the space in his/her head, not on paper/screen.

As someone else suggested, its best to go walk into a "Tall" space, look around, then go into a smaller space. I would try to sketch these spaces in plan and section. If you have the access to it, go onto a road between very tall buildings, and try to draw the section. And always draw a human at the same scale.

chose a building you would like to visit, then go into it with a sketch pad

do a perspective sketch to get the place

then  draw your sections - use Frank Ching books for examples - don't use 3D software until you can do it by hand.

i was gonna read frank ching, but i got high                                                                                        was gonna learn the whole damn thing, but i got high                                                                      now my section gots no zing, and i know why

because i got high, because i got high, because i got high

LA DE DA DA DA da ..

my freshman professor used to say that you should be able to fit melons in some spaces and grapes and apples in other spaces (mainly in reference to a model of your building).  section changes makes architecture interesting.  slabs and pancakes can be used sparingly to achieve an effect but should not be the whole building...

Volumes and voids also don't need to be square or rectangular, they can be any shape! have fun with it!

i second nicholas' suggestion but would add that you get a full figure image of a man or woman. scan it from a magazine- crop the figure out in photoshop-print it on paper. now sketch around it as per nicholas' suggesion but use the figure as your 'avatar' within the drawing. now, imagine the sense of narrowness of particularly narrow space..the height, , or for instance your position between one tree and the other and your height...and draw the representations around the figure

i was gonna put in my model some fruit, but i got high                                                                     was gonna fit da grapes and apples in real cute, but i got high                                                      ended eating up da motha' frickin' loot, and i know why

because i got high, because i got high, because i got high

LA DE DA DA DA da ..

Compression and release is one of the most important aspects of spatial design.  You need to commit to understanding it, both in plan and in section, which is what your post is about.

Here is one simple explanation.

Here is a quote.

Here is a very recent thread right here on Archinect about the same topic, in which one commenter makes the same suggestion I'm about to make:

It sounds like you are at the beginning of your education.  I strongly encourage you to read the book 101 Things I learned in Architecture School.  it does a great job describing in very straightforward language the concepts that many professors depend on flowery words and dramatic gestures to describe.

my space was gonna compress and release, but i got high                                                         was gonna squeeze ya then ya be free, but i got high                                                                     now my design's got no teeth, and i know why

because i got high, because i got high, because i got high

LA DE DA DA DA da ..                                                                                                                                    

Compression and release is one of the most important aspects of massage therapy.

i was gonna get a massage, but i got high                                                                                          was gonna help me with my cause, but i got high                                                                             now i'm locked up like julian assange, and i know why

because i got high, because i got high, because i got high

LA DE DA DA DA da ..

julian assange isn't locked up is he?  I thought he was hiding out in an ecuador embassy in london while running for senate in australia.

maybe you should sketch sections of the ecuador embassy in london

i tried to figure out jules ass's status, but i got high                                                                           was gonna find details to all dat fuss, but i got high                                                                          now my brain's a pile a-mush, and i know why

because i got high, because i got high, because i got high

LA DE DA DA DA da ..

Someone scored a J (or ten Js)!