Nail varnish impressions of stomata
One way way to 'see' stomata on a leaf is to take a nail varnish impression of it.
Method
The stomata leave clearly visible impressions in the nail varnish.If you use a graticule slide you can count how many stomata are on the leaf. In school biology labs it is a standard experiment to count the stomata on leaves of different speacies and try to explain the differences.
See also: Stoma, Care of living organisms, School Biology experiments and demonstrations, How-to's