This is the format that homework posts will be in. For today, if you do not have one already, sign up for a USACO account that you will use to take the contests with and practice with. Also, please review any concepts that you found difficult in today's class.
Here's the link to the practice problem we did today: http://www.usaco.org/index.php?page=viewproblem2&cpid=784. Here's the link to the solution: http://www.usaco.org/current/data/sol_lifeguards_bronze_jan18.html. Once you've made a USACO account, you will be able to submit your own solutions to past problems, such as this one.