UI Accessibility Improvements: The Recent Activity listing (defined as a table to the screen readers) on the Grouper home page has no meaningful labels

Problem:
The Recent Activity listing (defined as a table to the screen readers) on the Grouper home page has no meaningful labels.

Solutions:
Create a header row for the table portion of the table. This header row can be hidden using CSS. In addition, CSS could be used to define the table header row has having a height of 1px (or less) to make it non-visible.
Example code:
<thead>
<tr>
<th>Recent activity</th>
<th>activity date</th>
</tr>
</thead>