Your best bet by far in a situation like this? Get a good quality auxiliary flash, a flash bracket and off-camera shoe cord.... and possibly some sort of diffusion panel, bounce card or other light modifier.... and learn to use it!

Wow, you are teaching at the college level and I think I might be in Jr. High, lol. I did understand the jist, I think of most of that. Will look some of that up to better understand. Looks like my next purchase will be that flash........will continue to look for a quality used FF camera too. Will probably keep the 60D for backup/telescopic effect of crop factor, but eventually upgrade to newer generation of crop too................technology tends to cause folks to spend a lot of money, lol.

Here is a question for you: Have you studied and do you understand the exposure triangle and how it works? [ISO, Shutter Speed, Aperture] Each of these factors affects the others. So adjusting one will in general result in a necessary adjustment of the others in order to get the best balance in the captured image. Sometimes one factor has to be less than optimal in order to achieve a usable photo.

For fast-moving subjects, a fast shutter speed is necessary. This reduces the time for the sensor to capture light. It also helps prevent blur from camera shake when your lens does not have vibration reduction. As a result you must increase aperture and ISO, looking for a balance that will give you sufficient depth of field and better light-gathering ability. If the shutter speed is fast enough and an image still comes out looking blurry, the depth of field may not be enough, or your focus point is not on the subject [so you would be focusing on the foreground or background, or on an arm or leg but not the face].

As you noted, using an FX lens on a DX camera puts the crop factor into play. But the basic principles of exposure still apply in the same way. Switching that FX lens to an FX camera eliminates the crop factor, changing the angle of view, so to get the same composition as on the DX camera, you would have to move in closer. [If using a zoom, you could have stayed in the same place but zoomed in for the same composition. But this has no relationship to what aperture you are using.

The crop vs. FF is a debate that continues! The gap between them is getting smaller as technology improves. This results in making the decision which way to go even more difficult and requires more research to choose between cameras. Most digital cameras have many functions in common, the basis of a choice is in the differences. Comparing specifications this will be clearly seen. Reasons for choosing an FX camera include larger sensor size which suggests better image resolution capability, better low-light ISO performance with less noise at higher values, and a variety of "bells and whistles" that you may or may not ever use. Reasons for choosing a DX camera include lower price point, lighter weight, decent size sensor in newer models, and improved ISO performance [all of this in the newer models]. When I bought my first DSLR in 2012, I could not afford an FX camera, so chose the best of the crop-sensors at the time. It has served me well, and I still keep it as a back-up camera to my D810 purchased last fall.

Hope this helps.
Susan

Here's a pro perspective:

Every mode on your camera has a definite, legitimate purpose. And every mode has real limits!

You have to understand that every scene has a light level that requires a certain exposure. Your metering technique must be good enough to balance sensitivity (ISO) with exposure time (Shutter Speed), and the volume of light flowing through the lens (Aperture). For a given scene and ISO setting, you need a given size "bucket of photons."

Your meter is dumb. Stupid. It wants to see EVERYTHING as middle gray. If you meter a white wall, and set exposure blindly for that, you will get gray. If you meter a wall painted flat black, and set exposure blindly for that, you will get gray. So in difficult conditions, use an exposure target and white balance tool such as a Delta-1 Gray Card, or ExpoDisc, or One Shot Digital Calibration Target.

Oh, there are various matrix metering modes designed to give you a great exposure of "most" scenes, but they can all be fooled under certain conditions.

Manual exposure modes work best under stable, controlled lighting conditions, where the scene brightness range is limited to around 5.5 f/stops. A great example of this is an office or school classroom lit with 2'x4' fluorescent troffers. Another great example is a portrait setup with fixed lighting, used to photograph hundreds of school children. Another great example is a light tent used for product photography of small items for a parts catalog.

Program mode works best when you need to work in changing lighting conditions. If your camera has Program Shift capability, you can change the combination of aperture and shutter with the flick of a dial. The exposure remains in balance, but the aperture closes down as you slow down the shutter, or the aperture opens up as you speed up the shutter.

Aperture Priority gives you a fixed aperture and lets the shutter speed float with the light level. This is so you have absolute control over depth of field.

Shutter Priority gives you a fixed shutter speed and an aperture that varies with the light level. This is so you can use a speed that stops or blurs action.

Manual Mode gives you fixed everything... ISO, Aperture, Shutter Speed. This is so you can make a series of exposures that are all the same, provided the lighting is fixed!

There are many variations on these, of course, depending on your camera's features. If your camera has Auto ISO, it may be combined with other modes to really confuse things! (Just kidding. It's helpful, too.)

JUST as important as understanding the modes, is understanding light and its characteristics:

Scene brightness range (contrast range) (You need to control it or cope with it!)
Source specularity (pinpoint source vs. giant light tent, or hard shadows vs. no shadows)
Shadow edge acuteness control (specularity mixed with diffusion)
Specular highlight to diffuse highlight to shadow ratios (main to fill ratio)
White balance (dealing with off-color light sources)
Source color accuracy — continuous spectrum (Daylight and Incandescent) vs. discontinuous spectra (Fluorescent, Sodium Vapor, Mercury Vapor, Xenon flash tubes...)

JUST as important as all that is understanding your camera's JPEG processing limitations and raw image recording capabilities. There are legitimate times to exploit either or both raw AND JPEG workflows.

The point of all this? Read as much as you can about your camera and light and photography in general. Avoid the idiots who throw absolutes around like, "Never make JPEGs in your camera." or "Raw is a waste of time." or "Never use ______ mode." EVERYTHING on your camera has a purpose, or it would not be there. Learn its advantages and limitations.

Read the *Fine* Manual... even if it feels like water torture. Patience, grasshopper!

What works for you. But that sounds like "photography for electronics engineers": "signal gain over time"! I should look through my really old photo references and confuse everyone on the UHH with Foot-candles, Lumens, Lux, and Candles per Square Foot. Ever look at antique light meters? I'm sure I can find some other voodoo for exposure using Joules or Watts. Some people went through a lot of trouble figuring out f-stops and ASA/ISO to be basically unit-less universal values for photographers, and not physicists. Note, we also have guide numbers for Flash. My old cabled strobes with a power unit was rated in Watt-seconds. And what does that mean to most photographers? Why make something technical more complicated than it already is. I'll give you, I think of EC as off-set. How do you rate or measure your Light? Again, fine if it makes it easier for you.

But I've found overly technical stuff goes over most UHH'ers (and nearly everyone else too) heads. I've nearly given up trying to explain Diffraction -- sadly even basic quantum mechanics is beyond so many people.