The link below will take you to youtube for an excellent documentary series on the Presidents of the United States. It spends about 15 minutes on each president and highlights the events of his administration. This would be an excellent way to help prepare you for the exam.
The Presidents of the United States: Episode 1 (1789-1825)
This is just the first episode of the series there are multiple episodes and you can find those by navigating youtube, they are all on there.