(Originally published November 2012.)
Promethean World, the producer of the ActivBoard line of products, is a company for which I have mixed feelings.
On the positive side, I absolutely respect anyone trying to innovate, especially in a space which is traditionally unattractive - education. As a former student, however, I hate them.
Traditionally, using pre-composed visuals had many drawbacks.  ActivBoard does an excellent job of solving these problems. However, there’s a critical problem inherent to the field of technology which it can never solve: screen size. ActivBoards limit the amount of real-estate available to a teacher, which causes huge problems with learning for students.
ActivBoard, as with any medium contained to a small screen, forces the screen to be cleared constantly, because there’s just no space to leave something up. 
THAT’S A MAJOR PROBLEM FOR STUDENTS.
In an ideal classroom, all material presented will be new to the students. That’s quite difficult to take in, so good teachers take several steps to make it easier. For one, writing the title of what’s being discussed, along with a one-sentence overview of the topic is a huge help, as students who get overwhelmed quickly have a point to center themselves on what’s being discussed.  This is somewhere ActivBoard actually takes a step back — even slide decks addressed this with titles, however ActivBoard’s scrolling makes this nearly impossible.
More importantly, however, is the loss of the ability to leave equations in a specific place.
Humans have an extraordinary ability to subconsciously keep track of where things are. Having evolved for most of history without gps-enabled smart phones, this makes quite a bit of sense. What’s often neglected, however, is the translation of that fact to other visual mediums. When someone writes something on a board, a set of neurons in our brain fire to keep track of its location for future reference, as if sticking a tiny colored Post-it flag in the page of a book. 
With ActivBoard, students are constantly re-adjusting themselves to the location of content. Text scrolls on the screen and totally disappears. If it’s brought up again, it’s in a totally different place. The issues with this are particularly obvious when looking at the equations: equations are often interpreted in chunks (e.g. “∂v/∂t represents acceleration”), and students are forced to re-create this map in their heads each time.
Further, the lack of space requires students to remember more. Students are constantly fighting to learn the details of what the pieces mean, while the goal of a class is often to show the higher meanings. One can imagine students as similar to a computer - while they’re processing new information, it’s being stored in registers. However, there’s a limited amount of space for this sort of information, and it’s unfortunately fairly small. Once a student forgets something, they have to check notes to remember (which, of course, is slow), or at worst can’t remember at all.
Some have proposed handouts as a solution, but this totally neglects the spatial nature of a properly planned lecture display, and introduces new problems. Adding handouts causes a split in attention; any time the student needs to review the handout, they have to interrupt their current learning, switch to the handout, remember what they were confused about, and then find it, before finally switching back. Handouts have the actual effect of making one mistake virtually unrecoverable.
ActivBoard is certainly a step forward in some measures, but as a whole, it’s a poor choice of technology, and can only distract from the learning process. Beyond that, there aren’t really any obvious benefits; most of the addons (such as polling) are available as stand-alone modules, chalk/whiteboard pens are cheap, and simply having a digital copy of a whiteboard doesn’t present any major benefits in itself.
(I specifically call out ActivBoard in this article, but the criticisms I bring up are by no means specific to their product. Any of the “digital whiteboard” products have the same issues.)
1. Some of the drawbacks I’ve heard from teachers:
- It can be difficult to judge pacing. Without actually checking how long it takes to copy down important information, it’s difficult for teachers to be sure they aren’t moving too fast, particularly newer teachers, or those covering material relatively new to them.
- Likewise, it’s hard to judge size and color as the class will see it without actually putting the slides on a projector. Teachers are always busy (at a university with research; and at a pre-college level, with the number of students), and expecting them to find time to refine slide decks in the classroom is often difficult.
- It’s difficult to jump between slides if, for example, you’re short on time, or a student has a question.
- Live edits are impossible. If a student asks a question, teachers are left pointing to areas of a screen - far inferior to the rich annotations which can be done on a physical white/blackboard.
- Along the same lines, even designing annotations during the slide design process is difficult and time-consuming with the current tools. While it may take several seconds to circle something on the board, it often takes a minute or more to configure one in software.
2. The largest ActivBoard is 82”x46”. If we assume 14pt to be the minimum readable (as reported by Bernard et al), and a class size of at least 1,024 sq. feet, the font must be at least 2.4” on the screen to be visible. With line leading, we can easily call this 2.6-2.8”, which gives at most 14 lines of text space without clearing the screen. This is assuming one fills the entire screen, which would be totally illegible but little research seems to have been done on information density which could propose a more realistic number.
3. MIT 5.95J Lec 8 covers this at 15 minutes