A chair is easy to recognise and surprisingly easy to draw from memory instead of observation. You know it has legs and a back, so the hand begins producing a generic chair. Looking at the spaces between those parts offers a different starting point.
Negative space is the space around, within or between the subjects of an image. The Government Art Collection’s Rachel Whiteread resource uses this way of attending to space in its activities. For a simple drawing exercise, choose an ordinary object with clear gaps.
Draw one gap before the object
Set a chair or a group of kitchen utensils against a plain background. Keep your viewpoint fixed. Choose one bounded space, such as the shape between two chair legs and a crossbar, and describe it to yourself without naming the furniture.
Is the gap narrow at the top? Does one edge lean more than the other? Sketch that shape lightly. Then add the neighbouring space, comparing its height and width with the first. The object begins to emerge through the relationships between the gaps.
A simple paper viewing frame can help you keep the same crop. It also turns some open areas around the object into shapes bounded by the frame, making them easier to compare.
Use the spaces as a check
If the chair looks too wide, inspect the gaps before redrawing every leg. A space that is too broad or an angle that is too steep can reveal where the proportion changed. Correct lightly and compare again from the same position.
Finish by drawing the object normally on another page. Notice whether the first exercise changed what you observed. Negative-space drawing is not a replacement for every other drawing method; it is a practical way to interrupt assumptions and pay attention to the shapes actually in front of you.