The clock is placed low on our wall, but most of the class is at a complete loss as to the meaning of the numbers. Hence, we've been encouraging the use of the Montessori clock materials. First, a child simply matches the clock face to the "1 o'clock" or other corresponding label. Then the clock faces are stamped in the tablet and the child writes the time and draws on the clock's hands. A slew of other activities follow, then the child works on the "half past" clock faces.
Before introducing the "quarter to" and "quarter past" clock faces, I like to use this material that Mrs. T, designed. It is perfect for garnering an understanding of all the numbers and minute notations on a clock. All this takes time, though. The children are young, and learning to tell time is not easy. We encourage but must never frustrate. The goal of Montessori is to give the children the tools to succeed on their own.