The obstacle is the four pit props in the middle of the room being used to shore up mobile classrooms that were erected 20 years ago as a temporary measure.
The wooden posts, supplied by the county council's technical services team, have been put in to make the four temporary classrooms at the 366-pupil school for seven- to 11-year-olds safe for one more year.
Granby Junior, built in 1882, is now on the emergency repairs list and is scheduled for work in the 199899 financial year. It lost its outside toilets just five years ago.
Derbyshire County Council estimates that it has Pounds 6 million worth of condemned school buildings which are still being used, and it now has more than 700 pit props in 147 institutions.
Linda Lilley, acting headteacher at Granby, said: "Very often the children cannot see the words on the board or the teacher as she moves about.
"Because the pit props are in the middle of the room it is difficult to arrange the children into groups. Also, you can't use the middle of the room for things like drama."
Derbyshire estimates that it needs to spend Pounds 78 million to bring its crumbling buildings up to scratch; more than 20,000 primary and 1,600 secondary pupils are being taught in substandard classrooms.
It has 200 primary schools which were built before 1900, and around 50 primaries still have outside toilets.