chalkˈstone noun

1. A stone or piece of chalk
2. One of the white concretions that form round the joints in chronic gout, a tophus

chalk talk noun (N American)

An informal talk or lecture using explanatory notes and diagrams on a blackboard

as like (or as different) as chalk and cheese

Completely unalike

by a long chalk

By a considerable distance or degree

chalk and talk

The formal, traditional teaching method that relies on oral instruction and use of the blackboard

chalking the door (historical)

1. In Scotland, a form of warning tenants to move out of burghal tenements
2. A method of giving tenants notice to quit

chalk out

To trace out, as with chalk, to outline (a plan, etc)

chalk up

1. To make a special (esp mental) note of
2. To record (a score, etc)
3. To charge or ascribe to (a person or to a person's account, etc)

not know (or tell) chalk from cheese (usu derogatory)

To be incapable of seeing, or unable to distinguish between, important differences because of lack of knowledge or judgement

the Chalk (geology)

The uppermost part of the Cretaceous system in England