POST endpoints not working with Express - node.js

Question

I am writing a daily daycare reporting app using the PERN stack and I am having issues with some of my POST endpoints. The one below works correctly:
app.get('/classroomList', (req, res) => {
classroom.getClassrooms().then((classrooms) => { res.send(classrooms) })
})
app.get('/classroomList/:id',(req,res)=>{
classroom.getStudentsByClass(req.params.id).then((student)=>{
res.send(student)
})
})
app.post('/classroomList', (req, res) => {
classroom.createClassroom(req.body)
.then((classroom)=>{res.send(classroom.attributes)})
})
app.delete('/classroomList/:id', (req, res) => {
console.log('req received')
classroom.deleteClassroom(req.params.id).then((classroom) => {
res.send('Deleted')
})
})
}
However I have a few others that are written in the same exact way that come back with the error:
TypeError students.createStudent is not a function
The one below does not work and throws the aforementioned error message
module.exports = (app) => {
const students = require('../controllers/studentController')
app.get('/studentList', (req, res) => {
students.getStudents().then((students) => { res.send(students) })
})
app.delete('/studentList/:id', (req, res) => {
students.deleteStudent(req.params.id).then((student) => {
res.send('Deleted')
})
})
app.post('/studentList', (req, res) => {
console.log(req.body)
students.createStudent(req.body)
.then((student)=>{console.log(student.attributes)})
})
}
This is the controller that works:
exports.createClassroom = (classroom) => {
console.log('function accessed')
const newClassroom = new Classroom(
classroom)
return newClassroom.save()
.then(classroom => {
return classroom;
})
.catch(err => {
console.log(err)
})
And this one doesn't:
exports.createStudent = (student) => {
console.log('function accessed')
const newStudent = new Student(
student)
return newStudent.save()
.then(student => {
return student;
})
.catch(err => {
console.log(err)
})
}