Here is the link to it. https://studio.code.org/s/csd2/stage/1/puzzle/2
Students can navigate to any lesson material by starting at code.org (they must be signed in)
clicking on the view course
then clicking on the appropriate unit. Here unit 2
And then the correct lesson.
For teachers, there is usually a link from the lesson plan to the web resource but I do not see it on this lesson plan.
Hope this helps.