Ergonomy
Rubber bumpers
At least for primary school children (even if fifth-graders may be a more realistic target group than first-graders) it could be useful if the laptops had rubber bumpers. Young children may not be able to avoid throwing around or dropping an object or occasionally hitting something with it. Large, soft rubber bumpers could increase durability. Rubber bumpers would also increase friction and reduce the risk of accidentally pushing a laptop from a desk.
An alternative to rubber could be hollow polyethylene balls with notches to fit the edges of the laptop case, possibly with rubber on the underside to increase friction.
Polyethylene shell
A variant would be an enclosing polyethylene shell that could enclose the whole laptop like packaging material while allowing to open and operate the laptop. Pupils would have the option to use the laptop in its protective shell or without. The shell could give the impression that the laptop was extremely fragile and could provoke additional caution in its treatment while actually serving the purpose of an air bag.
The shell could allow some personal modifications (e.g. allow for a name badge) to make it a more personal item one might want to keep naturally instead of something that looks like packaging material.
Satchel
An inexpensive satchel could be built from plastic, bubble wrap and other cushioning material. A satchel would encourage carrying the laptop on the back, which is ergonomically better for carrying over longer distances and may decrease the risk of the laptop being knocked while being carried. A satchel would also decrease the risk of damage through rain and dust, even if the laptop is resistant. The price of a mass produced plastic satchel should be insignificant. The shoulder straps of a satchel could allow to suspend the laptop from the straps, reducing the weight-loading of the satchel to zero.
A satchel could include cat's eye reflectors for security on the road.
Retainer
A retainer for school benches could help to reduce the risk that a laptop was pushed from a bench accidentally, which can happen easily in a class with young pupils.