Believe it or not, The 84 is still fairly good all around. Nothing beats a dedicated hardware keypad (read: not a keyboard) for mathematics entry. I too delve into using the computer for mathematics. The calculator was way faster, entrywise. As for the 4-5 second delay in graphing, adjust xres, or get a faster calculator, or look into overclocking (not kidding). I also used an 89 for years, and 8 years later the 89 is still my go-to calculator.

To summarize : Computer for general homework == pain in the ass. Dedicated hardware is still the way to go.

Don't provide the end result, only the resources to create it. Print out all of the work. Printing is important because: a) it gives you a physical representation of the work, signed by the student. b) it allows you to thumb through them quickly and spot the duplicates (read: cheaters) c) allows you to prove this cheating relatively easily to administration, and give examples of non-cheating to compare to. Even though the students are all working towards a common goal, every image will come out different. Colors won't be exact, positions different, cut-lines different. Every image has a "signature", which makes duplicates and highly similar images (read: cheating with obfuscation) stand out when you physically look at each set of images individually.

Picking out the cheaters is much easier than it seems. Don't overthink this.

<sarcasm>Only if you don't believe in the power of Mac.</sarcasm>