2010a-147 21stcentury activityprograms adolescent adolescentbehavior adolescentdevelopment children computersandchildren constructivism(education) earlychildhoodeducation finland hightechnologyandeducation informationsociety internet internetandchildren massmedia massmediaandchildren massmediaandteenagers psychology safetyeducation safetymeasures socialconditions televisionandchildren ws462k61m2010