Congrats on completing the 250 box challenge!

There is a huge deal!

I could tell that you get the main idea. Your boxes look solid and proper.

The main issue that catches the eye is that you did not use the hatching lines to single out one side of the box. It was optional for this particular challenge, but still, I would recommend you start doing so. It works like extra line practice without stressing. And it really helps to understand which sides of a box are nearest to the viewer.

Also, I noticed sometimes you made multiple lines in the same place. You shouldn't do that : ) It's better to ghost line several times before making a stroke, and just to dare and make the final mark. And if it goes wrong, just leave it like that. Over time, such misses will become less and less.

Have fun in your next lessons!