| Link | Quote | Stars | Tags | Author |
| d5bfced | Educational technique needs a philosophy, which is a matter of faith rather than of science. | Hans Freudenthal | ||
| f813552 | Angles are measured by arcs, such that 360deg and 2p correspond to each other. | Hans Freudenthal | ||
| f5cac6f | Horizontal mathematising leads from the world of life to the world of symbols. | Hans Freudenthal |