What the worksheets need first.
Hand a child a page of clock faces to read and most of them lose interest partway through. Solving the questions does build something, but being able to read a clock on paper doesn't automatically turn into using a clock during the day.
Reading a clock is less about producing the right answer and more about tying "the time it is now" to "what happens next." Worksheets are good at training the first part. The second part grows in the moments when you wonder together: "what time is it now?" "how long until bath time?"
None of which makes worksheets a bad idea. But asking a child to read a clock they have never really watched leaves them with nothing to hold on to. Show them what a clock does first, and the printed dial on the page starts to mean something.