Here are supplemental websites and reading that may enhance your understanding of this topic.
Websites:
Topographical Maps from Regents Prep http://regentsprep.org/Regents/earthsci/units/mapping/topographic.cfm
Explore topographical maps from around the country.http://www.nationalatlas.gov/100topos/index.html
Animation on Reading Topographical Maps http://www.nps.gov/webrangers/activities/readingmap/
Printables:
Practice drawing Isolines on a map
Create a Tennis Ball Globe