Robbers have hit Dr WF Nkomo High School in Atteridgeville in Tshwane for the second time in a week, Gauteng Department of Education spokesperson Steve Mabona said on Thursday.
Mabona said robbers had broken into the school and stolen two smart boards and abandoned three in the school premises.
On Monday the school was also hit, with criminals stealing laptops and computers and stock from the National School Nutrition Programme (NSNP).
There have been a spate of robberies in the area.
On Friday last week, robbers broke into Masizane Primary School and tied up the security guard, before making off with seven computers, two tablets and all nutrition stock at the school.
Another school nearby, Thohoyandou Primary School, was also looted on the same day.
Education MEC Panyaza Lesufi said the thefts were "devastating".
"We are under siege. How can criminals be allowed to target our schools in this manner."