Last week, marked the 400th posting and one-year mark for the Revision Notes blog.

To celebrate, watch for these “400″ postings this week

• Best of Revision Notes: Links to the most popular postings of the last year.
• 400 Comments: Please Help me celebrate by collecting 400 comments by Friday!
• 400 Words Exactly: Writing Long sentences–here’s my offering at 400 words, exactly.
• 400 Online Research Tools: Fun tools for historical, economic or literary research.
• 400 Fun

400 Fun

400 Pennies Watch how several cars react when 2 teenagers drop 400 pennies in the middle of the road, and hold up traffic until every last penny is accounted for.