text: const grades = []
  class Grade {
    constructor(attributes){
      this.assignment_id = attributes.assignment_id
      this.id = attributes.id
      this.score = attributes.score
      this.student_id = attributes.student_id
      grades.push(this)
    }
  
    student(){
      return students.find(student => student.id === this.student_id)
    }
  
    assignment(){
      return assignments.find(assignment => assignment.id === this.assignment_id)
    }
  
    static find(gradeId){
      return grades.find(grade => grade.id === Number.parseInt(gradeId))
    }
  
    update(data){
      this.score = data.score
      $(`#${this.id}.score`).children()[0][1].value = this.score
    }
  
  
    colorChange(color){
      $(`#${this.id}.score`).addClass(`color-change-${color}`)
    }
  
    colorChangeBack(){
      $(`#${this.id}.score`).removeClass('color-change-blue')
      $(`#${this.id}.score`).removeClass('color-change-red')
      $(`#${this.id}.score`).addClass('change-back')
    }
  }
  