Teaching on Thursday!

On Thursday I will be teaching a lesson that will be observed by my professor. Last really during this time I was not that nervous, but this year it is a different story. I am really nervous and i cannot think of anything to teach. I am sitting here still thinking of how to teach Canadian Culture. Who would think a topic this board could be so hard? I feel that my brain is just in a freeze mood and will not let me think anymore. If anyone could help or have any ideas on how to teach this it would be greatly appreciated!