" but missing school to visit colleges seems wrong."
visiting to figure out where he might want to live for the next 4 years is wrong???
would you move into an entirely new part of the country without checking it out first?
Schools KNOW that students will be visiting colleges- mostly during vacations sure , but there is NO reason that a student cant be given homework assignments in advance and miss a few days of school. Trust me. It happens every year and the teachers are well aware of it.
here are some links to past and current discussions
http://talk.collegeconfidential.com/parents-forum/1918284-help-with-planning-college-visits.html
http://talk.collegeconfidential.com/college-admissions/1797245-how-important-is-visiting-colleges.html
http://talk.collegeconfidential.com/college-search-selection/1872769-plan-for-visiting-colleges-on-the-east-coast-ny-pa-ma-md-nj-ct-p1.html
http://talk.collegeconfidential.com/parents-forum/1909529-visiting-colleges-any-impact-on-admissions.html