{% if performer.teaches_for.exists %}
<h3>{{performer.first_name}} teaches at these schools...</h3>

<ul>
    {% for school in performer.teaches_for.all %}
    <li><a href="/schools/{{school.id}}">{{ school.name }}</a></li>
    {%  endfor %}
</ul>

{% endif %}

teaches_for = models.ManyToManyField(
        School,
        verbose_name="Teaches at this school",
        blank=True,
        related_name="teachers",
    )