I always find that students have trouble grasping how to tell time. Here are a few activities we do to practice this skill.
I would call out a time, and students would show me either by using a clock or by writing the time correctly on the whiteboard. When I called out "Show me!" they held up their clocks & whiteboards so I could quickly assess who got it and who needed some more practice. They switched items with their partners after each turn. It also kept everyone engaged and listening, and was really good practice.
I had my students tape a Time Check strip to their desk. During the day I would randomly call out "Time Check" and students had to look at the clock and record what time it was.