experiments by Redi, Spallanzani, and Pasteur
http://www.kent.k12.wa.us/STAFF/tIMlYNCH/SCI_CLASS/chap01/spontaneous.html
Dichotomous key activity
http://www.lnhs.org/hayhurst/ips/dichot/
classification
http://www.pbs.org/wgbh/evolution/change/family/
