As a Primary School Teacher I have a lot of experience with these.
Why do Teachers use them in Primary Schools?
Simply because they do the job required pure and simple.
Firstly they are washable- believe me that is SO important if Junior has written on his friend's shirt. Parents would be amazed at how often this happens in a day in a busy classroom.
Next they are robust- they deliver the colour well and evenly.
(A big tip here is to tell the child or person doing the colouring to leave an adjacent space which has a different colour until the first has dried or the colours will bleed.)
Children never listen to this in their rush to finish.
They feel the right size in the hands.
I myself use broad for 'big colouring areas' a far better investment for a parent would be a medium tip. This is especially true for the more adept 7 year olds and on.
Broad is fine for the younger children.
Now remember to replace the covers on the tips!
These things dry out and if the ink does not flow they are useless BUT
If you have one that has dried out a tip is to put it nib/point first in a jar of water and wait overnight if possible.
The ink should start to flow to the tip again. You can see that it has by the colour leeching from the bottom. A quick scribble on scrap paper or card and you may resurrect the pen for further use.
Pen lids- Teach you kids to put the lip on the bottom of the pen that way the all important lid is not lost, rolled away, eaten by the cat, chewed up, picked up in the vacuum or stuck all too often onto the wrong coloured pen.
Save the lids from worn out pens! You may loose an occasional lid and a quick replacement saves the pen.
Now a big tip here is if you damage a pen (A) and there is still a lot of ink left in the barrel take the inner out using a pair of snipe nosed pliers.
Take the old cartridge out of an empty pen (B) and push the cartridge of A into (B) making sure the tip inner is pushed into the hole at the top. If you open the things it is really clear what you need to do. A contact and continuous flow is all you need.
A few scribbles and the old colour of B say blue is soon changed to the colour of (A)
Hey presto a new useable pen.
A final tip is that those blacks get used first.
These are always the colours in short supply in schools.
So conserve them the most of buy a couple of Berol handwriting pens in black and perform the maneuver I suggest above.
All in all great pens that do the job