This applet provides an interface for displaying the slope field associated with a first-order DE \(x'=f(t,x)\). There is a nice collection of built-in problems, or you can enter your own. Clicking on the main graphical output regions draws either a direction vector or the solution curve based at that point. There is also a short list of check boxes to specify the step size. All-in-all, a very nice and simple applet.