At numerous points in the Harry Potter books it is made evident that Mr Weasley is somewhat...inexpert when it comes to his knowledge of the Muggle world (despite his inherent enthusiasm).
Mr. Weasley liked Harry to sit next to him at the dinner table so that he could bombard him with questions about life with Muggles, asking him to explain how things like plugs and the postal service worked.
“Fascinating!” he would say as Harry talked him through using a telephone. “Ingenious, really, how many ways Muggles have found of getting along without magic.”
(Chamber of Secrets, Chapter 4, At Flourish and Blotts).
“You’ll be paying now, then?” said Mr. Roberts.
“Ah - right - certainly -” said Mr. Weasley. He retreated a short distance from the cottage and beckoned Harry toward him. “Help me, Harry,” he muttered, pulling a roll of Muggle money from his pocket and starting to peel the notes apart. “This one’s a - a - a ten? Ah yes, I see the little number on it now...So this is a five?”
“A twenty,” Harry corrected him in an undertone, uncomfortably aware of Mr. Roberts trying to catch every word.
“Ah yes, so it is...I don’t know, these little bits of paper...”
(Goblet of Fire, Chapter 7, Bagman and Crouch).
I've given some reasons elsewhere as to why this might be. What I didn't consider in that answer was the possibility that he could have taken Muggle Studies, which is offered as a subject at Hogwarts.
“What are you doing Muggle Studies for?” said Ron, rolling his eyes at Harry. “You’re Muggle-born! Your mum and dad are Muggles! You already know all about Muggles!”
“But it’ll be fascinating to study them from the wizarding point of view,” said Hermione earnestly.
(Prisoner of Azkaban, Chapter 4, The Leaky Cauldron).
Of course, he's not completely clueless. Nevertheless, I would've thought that basic concepts like telephones and money would've been included on the Muggle Studies curriculum. Given his passion for all things Muggle I'd also have thought that Mr Weasley would have taken Muggle Studies if given the chance.
Is there any canon indication on whether Mr Weasley took Muggle Studies or not? If he did, why is he as ignorant as he is? If he didn't take it, why not?