chalk

as different as chalk and cheese (or like chalk and cheese) fundamentally different or incompatible. British

☞ The opposition of chalk and cheese hinges on their being totally different in all qualities other than their rather similar appearance.

by a long chalk by far. British

☞ This expression is based on the old custom of marking up points scored in a game with chalk on a blackboard, as is its opposite not by a long chalk meaning 'by no means; not at all'.

chalk and talk teaching by traditional methods focusing on the blackboard and presentation by the teacher as opposed to more informal or interactive methods. British

walk the chalk: seewalk.