We have standardized on 75" interactive panels to replace our projectors. In the secondary schools we are using the balance box to allow teachers to raise the panel for students to see in the back of the room. We still use projectors in large spaces.
David Spann CIO, McKinney ISD
Phone: 469-302-4081 | Fax: 469-302-2830
dspann@mcKinneyisd.net | www.mckinneyisd.net |
#1 Duvall McKinney, Texas 75069
In audio visual (AV) installations, the common standard used for determining screen size known as the 4/6/8 rule. This rule establishes that ideal viewing distance, in correlation with room size, should be four, six or eight times the height of the screen for analytical viewing (AV), basic viewing (BV) and passive viewing (PV). The advantage of applying this rule in classrooms is that the distances can be measured according to particular activities needing use of the screen.
By that rule, selecting the display as either basic viewing (BV) or analytical viewing (AV). In BV scenarios, you would divide the distance to the furthest viewer by six to calculate image size. In AV situations, divide by four.
The common use for screens was for basic instruction viewing instructional software content. For these uses, most applications were considered BV. AV was used for critical uses such as medical, engineering and occasionally for instruction. Under the old standard, the following common instructional spaces and average viewing distances yielded these common size outcomes.
Screens size when using 4-6-8 Rule
Instructional Space Furthest Student BV AV
Classroom 25' 91" Diagonal 72.5" x 116"
Training Room 35' 133" Diagonal 100" x 160"
Past classroom designs selected SVGA 800x600 or XVGA 1024x768 resolutions for display presentation (introduced in 1990). Teachers gave traditional presentations which looked acceptable. As times changed, sources and displays/projectors improved their resolutions, and presentations started using higher quality source materials.
The Infocomm DISCAS standard for image size determination considers the improved resolution of projectors and the impact higher resolution projectors and content has on the ability for viewers to see and understand the content. The standard incorporates several factors not previously considered, though DISCAS still has basic decision making and analytical decision-making guidelines.
For this example, HD or 1920x1080 (introduced in 2011) resolutions are assumed as the consumer industry has set this as the current baseline for our available product mix. The share of these higher resolution sources and displays/projectors have become common in classrooms. In BV guidelines, a font size is also factored. For our purposes, a 20 PT Font is used as a typical element in a presentation. Using DISCAS BV, 1080 lines and 20 PT Font, the recommendation for image size to furthest viewer is a factor of 5.
DISCAS yields more recommendations for larger screens than previously suggested. With the BV standard using a divisor of five instead of six, screens need to be 16% larger. Students expect better presentations full of video and high-quality imagery. This is true in all instructional spaces. Under AV guidelines even larger screens are needed. Screens likely to be specified when DISCAS is considered
Screens size when using 3-5-7 Rule
Instructional Space Furthest Student BDM ADM
Classroom Room 25' 110" Diagonal 87" x 139"
Training Room 35' 159" Diagonal 120" x 192"
This workup is for HD or 1920x1080, the required diagonal screen size for instructional spaces will increase as the sources and displays/projectors increase their digital resolution capacity i.e., 4K 2160x3840.
I have included the link to calculating Display Image Size for 2D Content in Audiovisual Systems
And the Epson calculator
AVIXA Display Image Size for 2D Content Standard, for those that want to read the standard.
Within the last year, we have started used Promethean AP6-70 interactive panels in the classroom. We went back and forth between 70" and 75" but decided on 70" because of a significant cost difference. We also put them on carts so they can be moved closer to students or setup for a group participation.Our sales rep indicated the size would be appropriate for 30 or less students and/or 30' x 30' size classroom. So far teachers and students are loving them and I have not heard of any size issues. I assume you can always move students around if they have issues seeing the panel.