In 2001, arson attacks - fires started on purpose - cost £56m to fix, a huge rise from previous years.
This money could have been spent on other things in schools, like improving computer facilities.
Arson and vandalism in schools are usually more common during holidays.
But in West Yorkshire alone, there were 33 deliberate school fires which were started while pupils were still in class.
Most fires are started for fun in rubbish bins and toilets. And because they are often small fires, they often aren't usually reported.