So far we have used the computer less in handling formal proof in mathematics education (with the honourable exception of the use of a language such as ISETL with the formal structure of set theory complete with quantifiers and logical implication.) “Theorem proving” and “theorem checking” software exist in certain contexts, and computers have been used to carry out lengthy checking procedures beyond the capacity of the individual, such as in the celebrated computer proof of the Four Colour Theorem (Appel & Haken, 1976). But standard computer technology still has the Achilles heel noted of the pioneering design of Charles Babbage in the nineteenth century: