&gt;  if you give a tough math problem to 1,000,000 students, and want to have a tutor walk them through the problem, you&#x27;d need to have 1,000,000 tutors. But there are probably only 20 types of mistake one can make on a given math problem. So if you had a &quot;choose your own adventure&quot; solution, one math teacher could, in a month, record lessons that reach a hundred million students at a personalized level.<p>Not quite. There may be 20 different types of mistake you could make on the problem (I would make a lower estimate, personally), but you can make them in several different places, and the influence of a mistake will be felt in the rest of the problem.<p>Udacity deals with this currently by never assigning complicated problems that might see a mistake in one step show up in a later step; this isn&#x27;t quite ideal as instruction, but it makes it possible to automate handling the assignments.<p>Some relevant cartoons:<p><a href="http:&#x2F;&#x2F;spikedmath.com&#x2F;240.html" rel="nofollow">http:&#x2F;&#x2F;spikedmath.com&#x2F;240.html</a><p><a href="http:&#x2F;&#x2F;smbc-comics.com&#x2F;index.php?id=3011" rel="nofollow">http:&#x2F;&#x2F;smbc-comics.com&#x2F;index.php?id=3011</a>