Design Guideline 1: Layout of Dynamic Worksheets
Avoid scrolling
Your entire worksheet should fit on one screen. Students should not have to scroll between the tasks and the interactive figure. We consider 1024x768 or 1280x1024 pixels as today's usual screen size which constrains the size of the dynamic worksheet. Using an HTML editor like NVU you can use tables to arrange text, images and interactive figures so they fit on one screen. If this is not possible, consider breaking the dynamic worksheet into several pages.
Short explanation
At the beginning of a dynamic worksheet, you should give an explanation of its content. Keep the text short (no more than one or two sentences) and write it in a personal style.
Few Tasks
You will usually add questions or tasks to make sure that your students use the worksheet actively. Place these tasks close to the interactive applet (e.g. directly below it). Don't use more than three or four questions / tasks to avoid scrolling. If you have more tasks, consider breaking your worksheet into several pages.
Avoid distractions
Make sure that your dynamic worksheet just contains objects that are relevant for the objectives. Neither use unnecessary background or purely decorative images, nor background music on the web page in order to not distract your students from reaching the objectives.
Try It yourself...
Task
Explore how the parameters of the linear equations change the corresponding lines in the 
Graphics View by changing the values of the sliders.
Try to modify the parameters so that the lines intersect at the origin of the coordinate system. How many solutions can you find?