I only said that they should try to draw without using a ruler. It could be a good way to improve their freehand drawing. But a ruler is a tool used in drawing like many others, so there is no problem with using it. And if they get the result that they want by using it, thats great.
Why do you give me a truck on this drawing Is this a Żuk? My name is writen as "Andrzej" not "Andrze"