Is free education really free?

Nigerian law on 'Basic Education' states that the first 9 years of education for all Nigerian children should be free.

Who is monitoring compliance? It is on record that most public schools ask students to buy their test books, exercise books and other learning materials themselves. 
Most public schools students also pay levies several times in a session. 
A good number of low income earners cannot cope with these financial demands and the resultant effect is that they will not send their children to school.

If the aim for Nigerian law on free Basic Education is to be fully realised, the government must step up action on monitoring schools to ensure that books and materials allocated to schools are properly utilised and that students are not asked to pay for what government has provided for their free use. 

Is free education really free in Nigeria?