Manipulatives
Interactive Demonstration Clock from Time-for-Time.com - this is helpful is you don't have a physical demonstration clock at home. Kids can play adjust minutes and hours on it.
This site has been around since my older kids were younger. Loads of resources. It has a demonstration clock, online games, and worksheets (though the worksheets aren't free anymore).
Posters/Charts
We were working on quarter to and quarter past in math and I wanted a reference poster for my daughter. I found some online but I made up this one to include some of the things that my daughter would often forget or has trouble with.
I made up a little poster and flashcards for my son a couple of years ago to review time concepts that I wanted him to memorize. The poster is great to place in a student's reference binder/organizer. And it comes with a set of six flashcards.
Telling Time to the Hour
Telling Time to the Hour Poster (TJ Homechooling)A simple poster showing the analog, digital and word form of time on the hour.
Telling Time to the Hour Cards - same printable as the Telling Time to the Hour Poster without the text below the clocks