Here's a video of an easy experiment you can try at home to simulate ocean currents. You only need a 9 x 13, some food coloring, ice in a zip-top bag, water, and a lamp.
This short video doesn't mention our content this week, but it does give some insight on ocean currents.
Question #4 on this page gives a great visual diagram for inquisitive kids.
And here's a very comprehensive site on ocean currents for older students.