Fire crews were called to Aspin Park Primary on Sunday, July 22, after a neighbour spotted flames billowing from the building.
North Yorkshire Police believe that ‘unknown individuals’ climbed onto the roof of the school and dropped a lit item into the room.
A governor of the school and Knaresborough councillor, David Goode, said: “It landed close to a bookcase which caught fire and spread to other parts of the room.
“The damage has been limited to one room but what I don’t know at the moment is how much it is going to cost.
He added: “The head and staff put so much effort into making the school outstanding.
“We have invested significant amounts into new book reading schemes over the past few months just to have all that work destroyed in one room.”
The classroom has already been gutted, with all burnt books and other destroyed materials removed and now the hope is to restore the damage before the pupils return from their summer break.
Head teacher, Nick Long, said: “This week has taken so much of everybody’s time in cleaning up, reordering new equipment and arranging for the classroom to be ready for September.
“It seems so disproportionate to the ‘enjoyment’ that those setting the fire get from it.
“I would also thank the emergency services for their prompt response, and our brilliant neighbours without whom the damage could have been a whole lot worse.”
The incident follows a number of other fires in the Harrogate District which are believed to have been deliberate, including most recently the fire at a closed down McColls on Starbeck High Street.
But Coun Goode believes the deliberate fires are an issue across the country.
He said: “There have been a number of incidents like this recently but it isn’t just Knaresborough - my son and daughter live in Sherburn-in-Elmet and one of the schools there has had its gym burnt down. There are spates of fires across the country.”
He added that he could not understand the ‘psyche’ of those responsible.
Coun Goode said: “They just don’t have an appreciation of the damage they do to the community as a whole with mindless acts of vandalism like this.
“It’s not only a lack of respect for people’s property but for their own health and safety - climbing on a roof is dangerous, why would anybody go and do something like that?”