I recently gave a brief introduction to the evidence for the Big Bang theory to Year 10 students as a part of the Centre of Excellence for All-Sky Astrophysics’s CAASTRO in the Classroom program. They do video conferences by scientists for school kids of all ages. If you are or know a primary or science teacher anywhere in Australia, then get involved!
Here’s the video. It’s already got one thumbs down on YouTube! Thanks, internet!
Letters to Nature 
I enjoyed it, so now you have 4 thumbs up! I especially liked Olber’s paradox and the final simulation (I’m a big kid at heart!).