teaching aids physics 56 English language 34 chemistry 34 analytical chemistry 33 civil engineering 29 German language 28 more ... examples 20 technology 19 teaching 19 electrotechnics 18 geodesy 18 computers 18 building constructions 18 general chemistry 16 programming 16 controlling 16 economy 15 programming languages 15 mechanical engineering 15 physical chemistry 14 engineering 14 teaching methods 14 inorganic chemistry 13 management 13 materials 13 circuits theory 13 economics 12 experiments 12 machine parts and joints 12 less ...