@foreach (Course course in Model)
{
   <tr class="table_row">
      <td method="post" style="width: 3vw">@Html.CheckBoxFor(modelItem => course.isSelected)</td>
   </tr>
}

private bool selected = false;
public bool isSelected
{
     get
     {
         return selected;
     }
     set
     {
         selected = value;
     }
}