Thanks for the video & the feedback, especially your attention to the student experience of going from one frame of reference to another. Here are some answers to your concerns:
The short answer is: it’s intentional, based on feedback from teachers. Originally, both tools worked the same with the (0, 0) point in the upper-left hand corner. This is consistent with how computer graphics work beyond CSF or CSD - but, as you mentioned, this isn’t the same way students learn coordinates in math class. After some piloting and feedback with classroom teachers, we received overwhelming feedback from CSF teachers that it made more sense to change the orientation of the (0, 0) point in CSF so it matched students’ mathematical learning and to better support teachers who wanted to integrate CSF activities into math classes (since the origin points would be the same in both places). However, we didn’t make this change to CSD so it could remain consistent with other applications of computer graphics and scaffold to other tools (such as AppLab) which also orients the (0, 0) point in the upper-left corner.
Students first start drawing in Unit 3 Lesson 3 of CSD. Even though this video at the start of the lesson explains that the origin point starts in the upper-left corner, we’ll look into making this more clear in the lesson plan to better support teachers & students who are building from CSF to CSD.
Dan - CSD Curriculum Writer