This article is from the Baby Proofing FAQ, by Sandra Smith, firstname.lastname@example.org with numerous contributions by others.
From: Narelle Clark
After reading a comment about marking a child's growth by the books they
can reach on the bookshelves, I recalled a sort of abstract child
proofing we have employed;
Instead of sorting books according to size or author etc we now
sort them in two ways i) big heavy ones at the base to encourage
stability in the shelves and ii) classified by topic as suitable
for a childs development. The higher the classification the further
they are from the ground!