“…This age trend has been demonstrated in both cross-sectional and in longitudinal studies (e.g., Culp, 1998;Sallis, 2000;Sallis et al, 2000;Kristjansdottir & Vilhjalmsson, 2001;Kimm et al, 2002;Barnett et al, 2002;Klasson-Heggebø & Anderssen, 2003;Norman et al, 2005). Since many popular forms of PA take place outdoors, it is interesting to note that adolescent interests in nature-based PA, as well as in studying or observing wildlife, decline with increasing age (and seem to decline steeply at the onset of puberty) (e.g., Bjerke et al, 2001;Kaplan & Kaplan, 2002;Bell et al, 2003;Brodersen et al, 2005). Stamps and Stamps (1985) and Hutchison (1988) reviewed the first decades of research on the relationships between social class and participation in leisure activities.…”