Simply, the method is named "openInWorld", with both, capital I and W. Squeak is case sensitive. On 8/15/10, john mcelhose <johbert at hotmail.com> wrote: > > I'm doing the exercise on p. 36 of 'Squeak by Example'. I get the message > openinWorld > self shouldBeImplemented > > MessageNotUnderstood: SBECell>>openinWorld > shouldBeImplemented > > What's the problem?