How to Mirror the Chrome OS Screen

  • Knox County Schools have placed many Chrome OS devices in several schools in the district. With this wide and rapid deployment, many questions are being asked as folks begin to use this "non-traditional computer" in the classroom. One of those questions is, "How can I mirror my Chromebook's screen onto my interactive whiteboard or flat screen TV?" Their are several options to do this, but there are pros and cons to each option.
     
    To help schools make their decision, below we have listed the pluses and minuses for each of the four current options available. The first two options, Chromecast and AirParrot, are wireless. The last two in the list, HDMI Cable and HDMI to VGA Adaptor, will tether the Chromebook to the teacher's desk or presentation station.
     
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Chromecast

  •  Chromecast    Chromecast 2
         
    Advantages
     
    The Chromecast 2 unit is relatively inexpensive, approximately $35.
     
    It allows, with limitations (See Minuses column), the Chromebook's screen to be displayed either on a TV or Projector that has an HDMI port.
     
    It can also display the content of a single tab of the Chrome browser on either a Mac or Windows machine. But only after an extension is installed in the Chrome software.
     
    In addition to the Chrome browser software, there are some apps available that have been enabled to display their screen content. 
     
    Concerns
     
    An installation of an extension for the Chrome browser software is required. This must be done for each user. If a student doesn't use the same machine each time, the software extension must be installed for that user on that machine too.
     
    The image that is displayed (mirrored) is only the contents of the Chrome browser tab. That means you are unable to show any shelf/dock items, setting, nor even the browser menu. The cursor is not displayed either!
     
    Even though you may have multiple tabs open in the Chrome browser, only one tab's content can be displayed at a time. If the teacher clicks on another tab, they must then go  back to the Chromecast selection tool and select to display the other tab. This is particularly troublesome when clicking a link on a website that happens to open a new tab or window. The teacher must remember to go back to the Chromecast selection tool to continue displaying the correct screen.
     
    If the webpage contains a video, the playback is not smooth.
     
    Installation of the Chromecast unit is relatively simple and easy as long as the HDMI port is easily accessible. Unfortunately, most TV sets are installed on wall mounts, making their HDMI ports impossible to reach. Also, most projectors are mounted too high to reach without climbing up on something.
     
    The Chromecast unit requires an electrical power outlet. Since many of the projectors' power is behind ceiling tiles, it is difficult to determine possible installation issues without someone climbing a ladder. 

AirParrot

  •  AirParrot  
     AirParrot
     
         
     Advantages
     
    If your school has already invested in Apple TV units, AirParrot is an inexpensive app to install on the Chromebook.
     
    The app works well, except for playback of embedded video.
     
     
     
     Concerns
     
    An Apple TV unit is required to receive the AirParrot signal.
     
    The current AirParrot is version 1. As with most version 1 software, it does have have a few annoying bugs, especially with disconnecting from the Apple TV. But the Mac and Windows version of AirParrot is already at version 2, so hopefully the bugs will be fixed in ChromeOS version 2.
     
    Playback of embedded video is extremely jerky. Full screen video locks the display, requiring a hard restart of Chromebook. NOTE: This is not really the fault of AirParrot. The problem is that in order to keep the Chromebook inexpensive, they are built with CPU chips that are slow and weak. As a result, it is impossible for them to both render video for the Chromebook's screen and then also render, encode, and send the signal wirelessly to the Apple TV.
     
    The audio signal is not sent to the Apple TV. A set of external speakers connected to the Chromebook's earphone jack will be needed. Thus tethering the Chromebook to the teacher's desk.  
     
     
     

HDMI Cable

  •  End of HDMI Cable    HDMI Cable
         
     Advantages
     
    An HDMI cable is relatively inexpensive.
     
    The entire Chromebook screen is projected, not just a portion.
     
    Webpages with embedded video are projected as smoothly as they are on the screen of the Chromebook. NOTE: This is because the HDMI port has its own dedicated video components that render the video and audio signals which are sent out over the HDMI cable. 
     
    If the teacher's computer is already connected to a projector or flat screen TV by HDMI, there is no need to purchase another one. Simply unplug the HDMI from the teacher's computer and then plug the cable into the HDMI port on the Chromebook.
     
     Concerns
     
    The Chromebook is tethered to the teacher's desk or presentation station.
     
    If students have their own Chromebook and need to project their screen, they would need to carry it to the teacher's desk to connect.  
     
    Using an HDMI cable does require either a flat screen TV or a projector with an HDMI port.
     
    If your school already has an Apple TV connected to the HDMI port of a projector, this solution would not work unless the project had an additional HDMI port. (Most do not have more than one.)

HDMI to VGA Adaptor

  •  HDMI to VGA Adaptor    HDMI to VGA Adaptor
         
     Advantages
     
    The HDMI to VGA adaptor is relatively inexpensive.
     
    The entire Chromebook screen is projected, not just a portion.
     
    Webpages with embedded video are projected as smoothly as their are on the screen of the Chromebook. NOTE: This is because the HDMI port has its own dedicated video components that render the video and audio signals which are sent out over the HDMI cable. 
     
    The majority of KCS classrooms already have a VGA cable connected to a projector. Thus, installing the adaptor is very quick and simple to do. 
     
    If you select to go with an HDMI to VGA adaptor, be sure to purchase one with an audio out port, like the one pictured above. VGA cables do not carry audio as HDMI does. So if there is an audio out port on the adaptor, you can connect an external set of speakers for any sound.
     
     Concerns
     
    The Chromebook is tethered to the teacher's desk or presentation station. 
     
    If students have their own Chromebook and need to project their screen, they would need to carry it to the teacher's desk to connect.