Children of 10-11 years of age were interviewed while undertaking a range of mathematic problems, most of which embedded mathematical operations in textually represented realistic settings. One problem, concerning a lift moving people in the morning rush, comprised a division-with-remainder problem in which children are required, conventionally, to introduce a particular realistic consideration in order to produce the "correct" answer. Another problem was an extended version of this, requiring children to comment on four competing answers produced by other children. Analysis of responses to the first of these two problems demonstrated that it was working class children who were especially likely to fail to produce the conventionally required answer. Having shown this, the paper concentrates on portraying the ways in which "failing" working class children interpret and respond to the two problems. Our purpose here is to contribute to understanding the difficulties working class children appear to have in negotiating the demands of contextualized problems.