Online homework/testing systems? I have been using Pearson's MyMathLab Global with my Engineering students.  I appreciate its convenience, but the students find its inflexibility annoying (if an answer is expected to be 1.5, then the system might not accept 3/2 as a alternative).  I have no experience of any other online system (WebAssign, WeBWork etc) - so I'm wondering if anybody here has been in the position of making a comparison?  And if so, what would you recommend?
 A: I used both WebAssign and WeBWork in the past; eventually I went with WeBWork and never looked back. Reasons: 


*

*WeBWork is free for students. Commercial publishers may offer "free" codes with a new book, but consider how much it will actually cost students when they can't resell their books. 

*Because of 1), there is less headache for instructors: no complaints from students claiming inability to pay for homework access, etc. Just one example: when teaching Calculus $n$, I found that instructor in Calculus $n-1$ picked a different (nearly identical) version of the book, to which the students' multi-semester access codes were tied. Consequently, the codes did not work for the actual edition. More time on the phone with WebAssign support for me...  

*The WeBWork problem bank is under your control. You can change things if you want to, or keep the same if you don't want. Commercial publishers keep churning out new editions of textbooks, in which exercises are reshuffled in some way. When this happens, you may end up picking problems for the whole semester anew. 

*WeBWork interface is very simple: there are few buttons, and they do what you expect. The interface of WebAssign is options upon options upon options, some of which will affect the students' use of the system in ways you would not think about. 

*I like being able to customize problems to match what I emphasize in class, to add a hint or clarify the notation. Or to drop a humorous campus-specific reference somewhere. :) 

*I think #1 is really important. The textbook industry is enough of a racket without students having to pay for homework access. 

A: Since this question was asked, there have been a some new projects


*

*edfinity. I haven't used it, but it looks like a better interface to WebWork problems, and it advertises as WebWork compatible.

*Ximera is a project out of the Ohio State University which aims at creating interactive textbooks. It could be used as a homework system. It is open source and you author problems in LaTeX.

*Khan Academy's exercise framework. Originally Khan Academy's exercises were written in Javascript using their exercise framework.  Now they use a domain-specific-language powered by Perseus.

A: Another interesting option is STACK. It assesses an answer by testing its mathematical properties, using CAS for equivalence (x^2-1=(x-1)(x+1) is the whole point), and has a number of other more subtle tests. It is designed for Moodle, but you can integrate it into any learning environment, either with an API at the quiz level or via LTI. We use it at my university for most first-year mathematics courses.
Some of its features are:


*

*It is free and open-source.

*Little coding is required to author questions.

*It separates validity and correctness, meaning students will not be penalized for an answer written in the wrong syntax (2x vs 2*x).

*It supports question randomisation, so students see different versions of questions.

*It lets you give pretty personalised feedback based on students' answers.

*It has good support for Physics and Engineering use, fx. supporting significant figures and SI units.

*There are a lot of sample questions available to get you started (see STACK demo and ABACUS).

