using technology to differentiate instruction

OK.  So we're trying to use technology to differentiate.  I'd like to choose one subject area for this and I think it will be math. 

Idea I) 
My first thought is to use the pre-test to determine areas of need, then organize a system for 10-20 minute whole group lesson followed by some "must do" work and 3 follow up activities tailored to the needs from the pre-test.  In this situation the teacher would probably set up the for "must do" and follow up groups. 

Idea II)
Another thought I had gives the students some power in their own learning.  I trying to figure out how to make one day each week the differentiation adventure.  For example, after a series of lessons on a particular strategy, I could begin the class with some multiple choice questions that students can answer using activotes.  I would create 3 questions (or 6 to get at 3 strategies we've been working on.  I don't need to know who answered which way, but it would be helpful to see the percentage of kids who struggle with each type of question.  Then I would ask the student to consider which questions they had the most difficulty answering.  If they struggle w/question 1 they could work on activity A.  If they struggled w/question2 they could work on activity B, etc.  At the end of work time, I could ask 3 different questions based on the same strategies and see if there was progress.  

My biggest challenge is to figure out how to use technology to meet the math goals.  It's easy to find fact practice sites, but our math goals right now include solving a variety of story problems that involve kids retelling the story, deciding the action described, then choosing a strategy.  I'm not sure where to find technology to support that other than having them create their own story problems by typing.  HELP!!