We had a tech support question today: "How can I drag around the function plot without moving the grid along with it?"

In Sketchpad, every function plot depends on a function definition, usually created by using the function calculator to enter an expression. (Alternatively, you can use a picture or drawing, but that's another topic.) And you can't directly change the expression by dragging its plot, which is why the coordinate grid also has to move. To do what the user asks, we need to drag in a way that changes the expression that defines the function.

Here's one way to do it:
1. Create a point.
2. Measure its coordinates and label the coordinates h and k.
3. Define the function in a way that translates it by h horizontally and k vertically.
The result is that dragging the point will drag the function plot as the user desires.

Here's a sketch that shows an example:
http://sketchexchange.keypress.com/s...ot-by-dragging

Happy Sketching,
--Scott