Recently we set up a bird box complete with a web camera in our garden and a pair of blue tits almost immediately claimed it as a nesting site.
The female built a cosy nest in which she laid eight eggs that she is now incubating.
You may like to let your class follow what happens so I have popped a direct link to the web area that contains updates of the birds activity on the sidebar of this blog.
Use the links at the top of the web page to see earlier activity.