don't know if this one was from Terror but i remember the plot being a couple who go to an isolated school in the country next to a pond, there is some creepy kid that keeps appearing, i think the guy drowns in the pond at the end.
There is a movie "Fear in the Night" (1972) - with Judy Geeson and Peter Cushing. It is about a couple who go to a deserted boarding school - only thing is the Principal (Cushing) still thinks there are pupils there but someone may be trying to send him mad!! There may be a lake and a creepy little kid but I can only remember Geeson's mounting terror!!
There's a tale of the unexpected about a couple that go to a school for sexy fun he handcuffs her to a bannister in the end then drowns leaving her trapped in the isolated school screaming for help....don't remember a child though there may have been one.