Children are said to lose on average a month’s worth of knowledge during their three months of summer vacation–with forgetfulness worst in subjects that require procedural and factual learning (like mathematics). Only those children whose parents encourage (or force) them to do some studying or other intellectually stimulating work during the summer aren’t affected.

“Summer learning loss” could really be named “vacation learning loss,” as any holiday where the mind similarly switches off for a period of time can result in forgetfulness. And while the problem is most acute in children–perhaps because few American adults other than teachers have the same lengthy summers–it can of course apply to adults on vacation as well. Blank stares from those just back from a trip abroad are common in boardrooms too.