Chalk up is an idiom which means to give credit to something or to attain something. It comes from the literal act in the 16th century of writing a debt that was owed to a store in chalk. Usually it is found in the phrase chalk it up to.
A chock is a wooden block used beneath wheels to prevent movement.
Chock-full means completely full. It is hyphenated as one word. Common misspellings are chockfull and chock full.
And chock-a-block is an informal word meaning crammed to capacity. Used mainly outside the US. Though there is an Americanized spelling, chockablock, listed in the dictionary.
Examples
Chalk up a victory for the little guys with the Waitangi Tribunal findings that slammed the Crown for its actions over the Rena disaster. [New Zealand Herald]
The 27-year-old will this weekend chalk up 150 games for his beloved club when the Lions meet reigning premier Box Hill at Box Hill City Oval. [Herald Sun]
They can chalk that gain up to Twitter’s nearly 20% stock surge the day after it posted surprisingly strong earnings. [USA Today]
Chalk it up to the 21 professional artists who have no problem creating short-lived drawings on the pavement at Water Street Marketplace in New Paltz. [Times Herald Record]
Both are canyons chock-full of fantastically shaped hoodoos and rock walls, something like Oregon’s Smith Rock State Park. [Oregon Live]
This bin has been chock-a-block over several months. [Grantham Journal]
The banquet of a five-star hotel was chock a-block on the rainy evening this Sunday. [Times of India]