You can add a Check Box to show the solution. This allows you to show a student more than just the solution but also the way he has to follow to find it. This is particularly interesting in exercises in which a student has to proceed more than one step.[br]Of course you can decide to show the checkbox always or just in case the student first gave a wrong answer.

In this exercise the student first has to derivate the function first, and than to calculate the number value for the given number. With the Check Box a student can control as well the derivate as the number value. And of course you can think of a lot of exercises with many steps.