thanks very much for that, sorted out my measurement prob.At the moment I am having trouble with divide command.I select an object, divide it into the amount I want,but they disapare as soon as I click anything.

hi.very new to sketchup.can anyone tell me why I am having trouble with my measurements.trying to build my backyard in 3-d.I size my shed and my glass house
in a plan view but as soon as I change my angle of view the measurements change.I no it is something simple I am doing wrong,any help would be greatly appreciated.
thanks
mark