The Educational System in Nigeria is divided into three(3)
Primary Education
Secondary Education which is also divided into two ( the junior secondary school and senior secondary school) both are three years each. 
Tertiary Education is a minimum of four years depending on the course of study. 
Now let's take a quick look at the problems affecting Nigeria's educational system.
1 Poor Funding
The government of Nigeria fails to fund the system due to high corruption. The educational system in Nigeria which is overseen by the ministry of education is facing inappropriate funding, thereby it has led to poor infrastructure, late or non-payment of teachers' allowance, and absence of good teaching aids. This is one of the major problems of the Nigerian educational system.
2 Corruption
This is another major problem in Nigeria which is affecting the educational sector seriously. Today they are different stories of lecturers taking bribes from students in exchange for good grades. This affects the sector badly, a student that bought his way to success won't be able to protect and defend his degree after he must have graduated.
Some lecturers even go extra miles to fail students in other to extort money from them or harass them sexually.
3 Lack Of Teaching Aids
Teaching aids are objects or devices used by teachers in other to enhance classroom instructions. Teaching aids can be books, computers, projectors, etc. These teaching aids make teaching very effective and it will also help the students understand easily. In most cases, these aids are not provided for teachers thereby making teaching difficult.
4 Poor Teachers Welfare
In today's economy, teachers are not appreciated, most of them are poorly paid, they lack basic packages. Even poor salaries are not paid on time and that is why Nigeria Schools go on strike. 
The problems stated above are just a few out of the many problems facing the educational sector, now let's take a quick look at the solutions. 
1 The government should provide adequate funds to acquire quality learning facilities. 
2 Teachers should be more appreciated and treated well.
3 Good teaching aids should be provided for teachers to make teaching more efficient and effective.
4 Teachers and lecturers should be Penalised and prosecuted strictly if found guilty of collecting bribe or doing any immoral activity.
Thanks for reading. If there is anything else you think should be added, you can add yours in the comment box. We learn every day.