Lesson 13 Activity 12

Working on trying to follow the directions for this one. When reviewing the Example Solution I see a string I do not recognize “mouseMoveCount++”.

Please explain where in the toolbox this string is and where in the lessons it’s function was explained. I might have missed it. Sorry.

Thank you,

mouseMoveCount++; is the same thing as saying mouseMoveCount = mouseMoveCount + 1; I think it is documented somewhere in the unit. I’ll look for it and post another message if I find it.


I couldn’t find it, but it still may be there somewhere … However, if you watch this video, starting about 2:45 in the video, they talk about the first short cut (+=) … then, in the next video “an even shorter shortcut” they introduce the ++. The nice thing about these videos is that the javascript library they use is almost identical to the one they use in code.org https://www.khanacademy.org/computing/computer-programming/programming/animation-basics/p/incrementing-shortcuts

1 Like

Thank you so much for looking and for the information about ++. I feel that any code that is used in the examples should be obviously presented so that they are easy to explain and students can easily reference.


I agree. They do teach the long way to do it and students can accomplish the task with that, but the answer key using the shortcut is a bit confusing if you haven’t seen it before.


I have found that there are a lot of these issues with the answer key showing something that needs to typed into the script section. For someone who is learning this with the students it is very confusing. I try to complete the stage, then check the answer key and see things for blocks that don’t exist in the library. I am also teaching the AP class using code.org and we have not had the same issues.


The CSP curriculum has been used for a full year already and they are still getting things like that cleaned up. This is the first year that CSD is being used nationwide, so I’m sure things like this will be noticed and cleaned up as well. So far, Code.org Staff have been very responsive and make changes daily to address these issues. On this particular one, it doesn’t impact students because the counter incrementation is taught in the course, just in a different way and it is the suggested answer key that has a shortcut in it. I’m sure by this time next year, CSD will have a lot of these things worked out.

1 Like

@kathryn_cogdell @bpenney

Hi Kathryn and Beth,

Thanks for posting about this. The last thing that we want to do is frustrate teachers, and of course it’s frustrating to have code in an exemplar that’s not reasonable for students (or even teachers!) to recognize.

If you see something like that, please consider it a “bug” in the course, and report it through the “Report a Bug” link in drop down menu on the top right of the page. It sometimes takes a few days for changes to show up on the site, but it’s a top priority for us to fix things to make it easier for teachers.

We really appreciate all the hard work that teachers are doing, both in teaching a new course, and in helping us to make it better.


@kathryn_cogdell @bpenney
Hello! Thank you for letting us know about the bug in the exemplar. I just fixed it, and the updated exemplar should be going out sometime later in the day/week.


1 Like


Thank you so much for your timely support and encouragement. I appreciate the time and effort that goes in to responding to each and every post with detailed and thoughtful responses.

I have enjoyed getting familiar with the CS Discoveries course and look forward to becoming more proficient in its implementation. Thank you for welcoming the comments and I will check in to the “Report a Bug” function.


I came to these postings with the same questions and thank you for the answers. I am still looking for where the suggestion of using mouseMoveCount++ is anywhere in the previous lessons in Unit 3.
I’m teaching and learning as the students, attempting the lessons before demonstrating them to my classes. When you wrote, “it doesn’t impact students because the counter incrementation is taught in the course”,- could you please reference where this is taught previous to Unit 3 Lesson13, so that I can review it and teach it to my class. Thanks for the assistance.

The counter pattern is taught, but apparently not the shorthand (++) version of it. I believe the first place we see it is in unit 3, lesson 9 where they introduce it as a method of increasing the x position of a sprite to cause it to animate. https://studio.code.org/s/csd3/stage/9/puzzle/3

Hope this helps!


1 Like