# Sketch Inside The Lines

If there’s one thing I’ve learned in art and in teaching, its that things rarely come out the way you plan.

Sketching inside the lines is hard. Getting all of your students to sketch inside the lines might be impossible.

If you’ve ever wanted to frame a student sketch or have them sketch in a particular shape,

students sketching outside the lines can lead to undesired results. But there is good news. Using a few simple tricks, you can change your sketch backgrounds from this:

to this:

## In order to introduce this method, lets take a look at a few graphs

Sketches are just a collection of coordinate points. That means that their coordinates can be transformed like like any other graph coordinates

If we wanted to reduce the list of points down to just those between given values, we could do that with filtering in the calculator. But because we can’t remove sketch points from a sketch, we need to instead limit the extreme values. The median tool can be very helpful for that:

Notice here, how the values greater than the upper bound or lower than the lower bound get snapped to the boundary. We can do the same thing in two directions:

### So how do we do that to a sketch?

First, take a minute to familiarize yourself with sketch transformations. There are a few articles, newsletters, and documentation samples that can get you started. Once you’ve done that you can apply the same clamping to the transformation functions!

``````clampedSketch = studentSketch.transform(
simpleFunction(`\median(-5,x,5)`,`x`,`y`),
simpleFunction(`\median(-5,y,5)`,`x`,`y`)
)
``````

Where -5 and 5 clamp the sketch in both directions. Changing those values will change the size and location of the clamps you want to set.

Want a challenge for yourself? Try these two challenges on screens 4 and 5 here.

• Challenge 1: Take the sketches in each of the boxes on the left side and arrange them in a grid on the right. You’ll need to clamp each part separately and move them to the correct locations.
• Challenge 2: Clamp the sketch so that it stays within the circle. For this, converting the sketch points to their polar representation will be very useful.
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