Two modest and instructive shows are now on exhibition at the Hirshorn Museum and Sculpture Garden. Both are full of minor works. That's the nicest thing about them. Masterworks mislead.

"The Cubist Heritage" contains no works by Braque or Girls, and only one Picasso. It is not a show of masterworks. It focuses attention on the bumpy, shadowed foothills, not on the lofty peaks. "Images of Children" is just as unpretentious. Its works vary widely in quality and style, but all of them show kids.

Both of these exhibits remind us that the history of painting is messier by far, more awkward, more confusing, than most museum surveys would lead one to believe.

The cubists, we've been taught, scientifically destroyed traditional perspective. They did to painted 3-d space what Einstein did to Newton. We think of them as earnest. But the cubists represented here were clearly having fun.

The myriad points of view, the cubes and cones and jagged places they borrowed from their betters, from Cezanne, Picasso, Braque, were more than sharpened tools for altering art histody. They were also toys.

The sight of Archipenko's 1913 "Movers" lugging cases up the stairs is bound to make one grin. There is a spendid little painting here -- "The Lamp" by Leger -- that, like many of its colleagues, is a kind of visual puzzle. Can you find the lampshade, the bowl of fruit, the cup? The earliest pictures here date from 1913. By the time these works were made cubism already was a game that everyone could play. And playing it was fun.Lyonel Feininger, it's clear, enjoyed adding to his painted steamboat billows of dark smoke described with nothing but straight lines.

The subjects of these pictures are remarkably traditional -- still lifes, landscapes, nudes, the faces of young women -- and the artists who produced them do not, from this late date, seem radical at all. The latter-day cubists represented here -- Storrs, Hartley, Zadkine, Laurens -- knew a good thing when they saw it. They turned to the new style because it set them free.

Frank Gettings, the museum's associate curator of prints and drawings, selected all the pictures in this show from the Hirshhorn's own collection.

"Images of Children" also is an in-house show. Mounted to mark the U.N.'S International Year of the Child, it includes works by Whistler, Homer, Eakings, Mary Cssatt, of course, Matisse and Brancusi. Some are sentimental, some, the Balthus, for example, are eerie and disturbing.

We are only now beginning to appreciate the breadth of the Hirshhorn's rich collection. A hundred other theme shows could be drawn from that horde. Such exhibitions teach.