The NSA has provided cybersecurity curriculum free for high school teachers (or anyone else) at teachcyber.org. There is also a high school/community college instructor (Tobin Shields) from Mt Hood Community College who is willing to share his entire massive curriculum complete with labs and videos with anyone who wants to use it. You can find this high school curriculum at http://bit.ly/HS-Cyber.
In addition to high school curriculum, students can participate in GenCyber camps and CyberPatriot teams at their high school. GenCyber camps have been held at Lake Superior College for the past four summers in June. CyberPatriot coaches can download all the materials for competition free on the CyberPatriot website.