UK Government power structure chart?

[Jchina09]

Greetings,

I am from the United States, and am working as an English teacher at a university in China. My students have expressed an interest in learning about the system of government in the United Kingdom. Since I had never studied the UK politics and government, I have been doing some reading to educate myself so that I can teach a class on the subject to my students. However, since many of my students have only limited English ability, I have been trying to find a chart or diagram laying out the basic power structure of the British government and the relationships between each component. Repeated Google searches have all come up empty.

Does anyone know where I might find a decent chart that could be duplicated on a blackboard?

Thank you for your help.