Time is such a difficult topic to be learn by children. Its typically because it is an abstract concept. You can not touch time, you can feel time, you can not eat time so it is hard for children to learn time. In order to teach children about time, teacher need a very interactive and comprehensive approach to make sure that children are able to master this topic.
There are many reason why children find it hard to learn about this topic. One is normally many adults fault; especially clock manufacture. They usually use the sense of art to design their clock and the most important is the commercial value. They (the manufacturing company) don't care about our children in learning time. So that why we can find that there are many types of clock and watch in the market. Some with all 12 numbers, some Roman numerals, others with only 12, 3, 6 and 9 numerals, and still others with no numerals at all!
Other than that, the reason why children find it difficult yo learn about this topic is that time is measured using a mixture of base 12 and base 60 system, and when it extended to days, weeks, months and years, it uses base 7, 4, 28, 29, 30, 31 and 365 systems. It is so difficult for children to remember all of this because normally they are doing basic operation with the base of 10 not 4 not 7 not 12 and not even 356!
Time is absolutely influenced by the surrounding such as seasons changing, the movement of the sun, hands on a clock face and digit changing displays. All of this are absolutely new for certain people. For example, Malaysian and Brunei children are not facing any season changing such as autumn, winter and summer. So it is quiet hard for them to learn and understand about this without any previous knowledge.