As is clearly indicated by the use of lacing cards. The advanced class on the other side of the playground gets pot holder looms.

Tterrace, we called them "lacing cards" back in the late 50s.

[That kind of rings a bell, thanks. - tterrace]

Somehow I expect Bing Crosby to show up and sing, "Would You Like to Swing on a Star?"

Just to the right of Pigtail Girl.

She looks like she just sat down on someones Peanut Butter Sandwich but she can't move until the picture is taken.

That string and card thing has stirred up some ancient childhood memories, buried since... well, childhood. I remember using various colors of knitting yarn and winding up with a rudimentary needlepointy kind of thing. Sort of the equivalent of paint-by-numbers; presumably there was a name for it. So glad the exposure caught the kid on the swing; brings the scene even more to life. The ones looking back at the camera help, too, as well as the look of genuine delight on the face of the teacher (keeper?).