A ball — visuco

Challenge 1 of 20

Back to writing whole lines, with a comment above each gap saying what it should do. One habit to start as you mean to go on: where the comment says the middle, write width / 2 rather than 200. Both draw the same circle today.

Write the line.

Your code JavaScript

Write the line.

Console print() output

0 / 30 frames · 400×400

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Penalties: none this run

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Lesson Put It All Together

Everything from this course in one place: number variables, words, the four sums, and placing shapes with width and height.

As in the last topic of Course 1, each picture has missing lines with a // comment above telling you what to write. The difference is that positions should now be worked out from variables rather than typed as fixed numbers. If a comment says "60 left of the middle", that is width / 2 - 60, not 140.

It gives the same answer today, but it says why. Written that way the picture still holds together if a number above it changes, and it reads as a description of the drawing rather than a list of measurements someone once took. That is the habit worth building.

Two things make these easier than they look. Most pictures are symmetrical, so a line you have already written is usually most of the next one — copy it and change the number that differs. And where a value is already sitting in a box, use its name rather than the number inside it.

Take the lines one at a time and press Run after each. A picture that is half right scores partly right, so you can watch yourself getting closer rather than guessing at the end.