In a hurry to submit their answer booklets to invigilators, some candidates forget their expo (materials used for examination malpractice) in the booklets, the West African Examination Council has said.

The council also noted that some other candidates use different answer booklets from its authorised copies.

Its Public Relations Officer, Mr. Demianus Ojijeogu, who confirmed this in an interview with our correspondent, however, added that the council had reduced the incidence of impersonation in its examinations through its biometric registration process.
He said, We encounter malpractice during the examination and during marking. Some leave the expo in the answer booklets. We see that all the time. Others use other answer booklets different from the councils own. But, we discover these things during marking because the booklets do not have our serial numbers and they are not usually signed by the supervisors. Supervisors usually sign the booklets before they are given to the candidates.
http://yusbaklee.com/2016/09/23/some-candidates-forget-expo-in-answer-booklets-waec/