Empleo (4) Paper (3) Papel (3) Cell phone systems (2) Cell phones (2) Internet (2) Labor (2) Teenagers (2) Youth (2) Tools (2) Time (2) Telephone--Equipment and supplies (2) Surveys (2) Schools (2) Learning, Psychology of (2) Families (2) Education (2) Design (2) Dependency (2) Communication--Technological innovations (2) Dependencia (2) Teléfonos móviles (2) Estudios (2) Teléfono móvil (2) Teléfonos (2) Encuestas (2) Internet (2) RED (2) Educación (2) Diseño (2)