Those incidents have intensified calls for authorities to tighten monitoring of school feeding schemes, raise hygiene standards and make learning environments safer for children.
Ugandan police are investigating the deaths of four pupils at a school in the capital, Kampala, which they suspect may have been caused by poisoning.
The head teacher of the school has been arrested to assist the investigation, police said.
According to the school, eight pupils ate oranges shared by a fellow pupil. Five of them, including the four who later died, began vomiting.
Three of the pupils died at home. The fourth died while receiving emergency treatment at a hospital.
A police spokesperson, quoted by local media, said detectives would visit the village where the oranges the pupils ate came from.
The deaths come as concern grows over health and safety conditions in schools across Uganda.
In earlier cases, suspected contaminated food and exposure to harmful substances left pupils in hospital with stomach pain, vomiting and breathing difficulties.
Ugandan media shared videos of grieving parents describing their children's final moments. Some parents accused the school of failing to give clear and timely information.
Police offered condolences to the bereaved families and the affected community and said more information would be provided in due course.