Washougal — Third-grade students in Lucia Willeman's class at Cape Horn-Skye Elementary School were real "Artifacts Detectives" as they brushed, washed, measured and categorized truly old stuff, thanks to a Teaching American History grant and to the Clark County Historical Museum. The museum supplied materials that were gathered in 2004 as the site of the future Vancouver Convention Center was excavated and prepared for building. A Portland archaeological firm was called in to document and map everything at the time, but the sheer number of artifacts — 90,000 — was overwhelming. In the end, about half of it was boxed up without being cleaned or studied. The Clark County Historical Museum has developed several classroom teaching kits based on these artifacts, which date from 1870 to 1920, and other local teachers like Willeman have developed their own. "You have to take your time to do it right," said third-grader Connor Esteb. "This is fun, but it is also hard work."