Python Flask Basics Character Builder Loop Nested Items

what am i missing here

the code wont work

flask_app.py
from flask import Flask, render_template

from teachers import TEACHERS

app = Flask(__name__)


@app.route('/')
def index():
    return render_template("teachers.html", teachers=TEACHERS)
templates/teachers.html
<ul class="teachers">
  {% for teachers in teachers %}
  <li>
    <h2> {{ teacher.name }} </h2>
    <ul> class="courses">
      {% for course in courses %}
      <li>{{ teacher.course }}</li>
      {% endfor %}
  </li>
    {% endfor %}

</ul>