Garissa , Kenya ( CNN ) The sign painted onto the school entrance wall reads : `` Youth is a mistake , adulthood is a struggle , old age is a regret . '' The black humor of the message provides some light relief for a school that lives in constant fear of a terrorist attack because of what is taught inside its walls . The students ( aged 8 to 14 ) at the Ibnu-Siina school in northern Kenya are getting a so-called `` Western '' education , taking lessons in subjects like mathematics , science and English . But it 's an education that Al-Shabaab -- the Somali-based terror group -- is trying to prevent the children from obtaining , according to the head of the school . `` These men , Al-Shabaab , want to make sure everything goes negative , '' headmaster James Ndonye told CNN . `` They want to make sure they terrify the teachers so they go to their homes -- so the kids in this area do n't get what they deserve . '' Al-Shabaab militants have launched a series of deadly attacks over the last few years in the region mostly targeting Christians . Many of the math and science teachers in this area are Christian . In early April , Al-Shabaab brutally massacred 147 people at Garissa University in northern Kenya . It was the group 's deadliest attack to date . The gunmen would have driven down the road past the Ibnu-Siina school -- and its single unarmed guard -- to get to the university , only a few hundred meters away . Kenyan teachers and students alike are terrified . `` The University College of Garissa was the only and first university college in northern Kenya . We were happy when we got it a few years ago , '' explained Garissa Regional Governor Nadif Jama . `` Today it has been closed . That is Al-Shabaab 's mission , '' Jama said . `` That is what they want . And that is nothing but destroying the fabric of our being a civilized society . '' And it 's not just in Kenya . Terrorist groups across the Sahel region are waging war on schools , teachers and students . In northeast Nigeria , the Islamist militant group Boko Haram has been waging war against the government -- and the civilian population -- for several years . Most notoriously , perhaps , was Boko Haram 's kidnapping of around 270 girls from a boarding school in Chibok , Borno state , last April . But the group has also carried out numerous other attacks on schools , slaughtering young boys and girls as they sleep in their dormitories . Last year in Garissa , James Ndonye lost five of his 11 teachers amid rising fears of an Al-Shabaab attack on the school . He replaced them , but it was n't easy . Yet despite the ever-present threat of terror , Ndonye has stayed to help the children . `` I risk my life because -- for this class , there 's a target we have for last year ... and I love that class very much , '' Ndonye said . Exclusive : Tracking the killer behind Garissa massacre .
Looming threat of Al-Shabaab has terrified students and teachers in Kenya . The group is suspected to be behind a series of attacks on schools this year that have left more than 150 people dead.