Alan,
 
Mr G Johnston wrote:
"With respect to the possibility of using observation hives for educational purposes, I have
found that it is useful to build it basically out of wood with only one obsevation "window". This
stops moisture build-up in humid climates, which you may or may-not experience in your part
of the world. In our situation there was a lot of moisture build-up which the bees struggled to
rectify because the hive entrance only consists of a tube. This led to quite a large infestation
of waxmoth (Galleria sp.) which, although detrimental to the bees, was interesting in itself."
 
   Our observation hive has glass on both sides, and is three frames high.  Having glass on
both sides allows us to see the queen, who likes to hide.  I think four would be better to help
relieve congestion.  It also contains an area at the bottom with a screened circle, over which I
can put a feeder jar.  For ventilation, (and it's humid here too,)  there is an area at the bottom
(opposite side from the feeder jar) with a large double screened open area, which then leads
to a wood block at the end for the tube to go outside.  (Double screened to keep young
fingers from getting stung...)  There are also three screened 1 1/2 inch holes at the top.
 
   Here's an end view, (if this comes through...)
                                / ---screened holes (3)
                         __  V __
                        |  |___|  |
                       ||_|      |_||
                       ||            || <---glass (both sides)
feeder           ||            ||
(screened    ||            ||            /----exit block (at far end)
 circle)                  ...           ___V_
            \          ||_        _||     |        |
    ____V____||  |       |  ||__|____|__ <---large double screened opening (width of hive)
    |  |            |___|      |__|               |  |
    |  |_______________________ |  |
    |___________________________|
 
(That was hard to do in ascii!)
 
   It is important to dimension the parts so that proper beespace is maintained between
frames and glasses and between the frames (vertically.)  I use small tacks which stick out
sideways at the bottom of the frames to maintain this spacing from the glass.  Use standard
size frames so you can swap frames of brood out to a field hive.
 
   I pull a thin wire under the glass to separate it from the wood when it is propilized in place.
Use thick window glass so it does not break with manipulation (and/or have spare glass
available for "emergencies," which are no fun.)  The bees fill the frames with brood quickly
and must be manipulated (replaced) more frequently than a normal hive, because of the
abnormal small size.
 
   Observation hives are very useful to watch for honey flows and for instruction.   I take mine
"on the road" frequently with duct tape over the entrance (and the wall tube inner end.)  The
kids love it!
 
Have fun!