Originally published in 1973, this is a selection of the educational writings of H. E. Armstrong, edited with a full introduction by W. H. Brock. Henry Armstrong (1848-1937) was a controversial and energetic publicist for reforms in science teaching and curricula. He was concerned to make teaching at all levels less didactic and authoritarian, more practical and experimental; where possible a student should be prompted by his own curiosity, and should learn things first hand. He called his approach 'heuristic' - meaning learning through discovery - and sought to establish it through public platforms like the British Association, schools and through his own training of teachers. In his introduction Dr Brock offers a historical critique of Dr Armstrong's methods and achievements, and considers to what extent he can be seen as a progenitor of subsequent curriculum reforms.