Highlights provides near real-time visibility of student activity in their Google Chrome Browsers. Because of this, Highlights can use more school network bandwidth than Dashboard, Workspace or Analytics.

 

Highlights communicates between teacher and student devices using different types of messages. 'Heavy' messages that contain screenshots of students' Chrome screens are the types of messages that impact more on Highlights bandwidth usage.

 

We have tested and are continually optimizing Highlights so that it provides teachers valuable, up to date information, while minimising bandwidth usage. Specifically:

• When a teacher opens or manually refreshes Highlights 'Current Screen', connected student devices in the class will send a single screenshot.
• While a teacher is viewing Highlights 'Current Screen', connected student devices send a screenshot when the student opens a new tab or closes a tab in their Chrome Browser
• If a student opens or closes multiple tabs in quick succession, a screenshot is sent after the final action
• When a student moves between existing tabs in Chrome, a new screenshot is not sent
• If Highlights is not in use, student devices will not send screenshots
• While a teacher is using Highlights Browser Tab, Activity Viewer or Snaps, student devices will not send screenshots
• The bandwidth used by each screenshot depends on settings in the Hapara Admin Console in the Highlights page - allowing bandwidth usage to be controlled by the Administrator. 

The bandwidth used by individual messages depends on many factors, for example:

• Bandwidth used by a "light" message depends how many tabs the student has open. An average "light" message is around 1 kilobyte.
• Bandwidth used by "heavy" messages depends on the Image Quality setting in the Bandwidth Control section of the Hapara Admin Console, and how well the student's screen image compresses. With the default Highlights settings most "heavy" messages range from 30 to 60 kilobytes. Lowering the image quality in TDAdmin reduces this size to around 10 kilobytes.
• The default Highlights Activity Viewer setting is set to refresh the student information every 2.5 seconds.

Because the frequency of these events depends on the student and teacher usage, the average bandwidth used by a classroom of students can not be reliably calculated by multiplying the above figures by the number of students or teachers. The total bandwidth used is entirely user and school specific, depending on how Highlights and Student's Chrome browsers are utilised.

 

The "peak" bandwidth load occurs when a teacher opens or manually refreshes the Current Screen of Highlights, as the devices of all students in the class are asked to provide a screenshot. To reduce this peak, Highlights deliberately spreads these requests across a few seconds.