2006h-739 birthcontrol childdevelopment childmentalhealth childrenandtheenvironment conservationofnaturalresources crowdingstressinchildren dd9668 developingcountries dwellings economicaspects economics ecuador environmentalaspects familyplanningservices forecasting hb850p8341975 hq766 internal migration militarypolicy olderpeople population populationcontrol populationforecasting populationgrowth populationpolicy problem-basedlearning projectmethodinteaching psychologicalaspects publicpolicy socialinteractioninchildren studyandteaching(middleschool) unitedstates ws105