This time I wanted to avoid this problem, so I explained everything to the students really carefully. I also picked up the drawing, put a sheet on it and said that this is exactly what I don't want from them. That the goal is to enlarge the given structure to the entire drawing. Everyone again nodded that they understood me and how else, about 4 students drew a leaf in the middle of the paper.
I also picked up the drawing, put a sheet on it and said that this is exactly what I don't want from them.