Boko Haram
Boko Haram militants abducted almost 300 girls from Chibok in 2014.
UNICEF has been able to reach 67,000 students by setting up temporary learning spaces and renovating and expanding schools.
The conflict has forced more than 2,000 schools to close in Nigeria, Cameroon, Chad and Niger.
WHAT'S HAPPENING
A police spokesman said three females carried out the bombings.
The country is part of a 8,700-strong task force comprising troops of Chad, Niger, Nigeria and Benin, aimed at destroying Boko Haram.
Suspicion is likely to fall on Islamist militant group Boko Haram, which frequently uses suicide bombers to hit soft targets.
"Boko Haram has once again sent us into mourning."