I received maqueen v4.

1. About packaging and hardware
Good progress:
-now a small booklet is included.
- mounting M3 holes are marked - it's desirable to do so in online instruction as well
- pins for 2 servo provided - it would be better to mark which ports are used there as well (is it p17,18?)

2. Map of Patrol line

- iI received 2-rings map while in online documentation it's oval track (I do not complain, just mark a discrepancy)

- looks like the distance between sensors and size of line are the same (15mm?). I had an observation a few years ago, with my own model, that more optimal is having sensors a bit (2-3mm) wider than size of line

3. I've published a programming course with maqueen in Russian, for age 10-13, 12 academic hours (45min). and soon to start on continuation (more exactly. it's rather material for a teacher)
Should Dfrobot have an interest in English version of the course, we may discuss it.

Mikhail Semionenkov, educator. PhD
Dear Mikhail Semionenkov,
Thank you so much for your support, feedback and suggestion.
We are really appreciated it.
Firstly, the line-tracking sensor distance are too difficult to modify due to dimension limits.
But we will improve the map line width.
Secondly, we will modify the map shown online.
Finally, the servo pin does not used the IO interface in micro: bit is that it designed with IIC communication for easy use. This is the special servo interface.