"We have real problems. Some teachers have been posted to schools but they are not enough. We do not know how long this will take. Learning is yet to start in many schools. It will not be possible for a single teacher to handle up to seven streams," he added.
Mr Oyuu said in some schools, the situation has been worsened by a lack of books . While the ministry rolled out distribution of text books this week, he said many schools are yet to receive books for Grade Seven learners.
"There is a serious shortage of teachers. That is why not much is happening in many schools. But as a union, we will continue to push for the employment of more teachers," he said.
The union wants the Teachers' Service Commission (TSC) to employ up to 120,000 teachers to help fill teaching gaps that exist in nearly all educational institutions.
Mr Oyuu said the requirements laid out by the Commission for those who want to teach Grade Seven students have locked many teachers out.
In the requirements, only teachers who scored C Plus in their Kenya Certificate of Secondary Education (KCSE) examinations are eligible to take up JSS teaching jobs.
On Saturday, however, the teachers' union asked TSC to consider lowering the requirement to C plain. Mr Oyuu said most teachers who went through Teachers Training Colleges can handle junior secondary.
"I have visited several schools and nothing is happening. In one of the schools, they did not even have text books," said the Knut boss.
As part of the efforts to address the challenge, Knut wants the Ministry of Education to fast-track the transfer of teachers who had been affected by the delocalisation programme, back to their home counties.
Oyuu said teachers have been suffering under the delocalisation programme.
"Delocalised teachers have suffered for a long time. Our belief is that teachers were supposed to be back to their home counties by the end of January but this has not happened," said Oyuu.
His comments come days after a section of teachers from Trans Nzoia County staged protests to demand transfer to their home counties.