In the early 1980s three researchers at the Federal University of Pernambuco, in Brazil, Terezinha Nunes Carraher, David Carraher and Analúcia Schliemann, went to the markets of Recife to talk to children and teenagers aged 9 to 15 who sold coconuts, corn and popcorn. They posed as customers and set sums at the moment of purchase. Later they came back with the same sums written on paper, school-style. The result, published in 1985 under the title Mathematics in the streets and in schools, became famous. In the market, the children got about 98% of the sums right. With the same sums presented as word problems, about 74%. As written computation exercises with no story, about 37%. The book the authors published later, in Brazil, summed up the situation in its title: Na vida dez, na escola zero (1988), “ten out of ten in life, zero at school”.