Old paintings on school slates are certainly “make do," creations of sorts, as slates were certainly easier to come by than canvases, and I especially love double sided ones, taking advantage of the nature of the slates themselves. This one seems to have been expressly made to be flipped, offering a snow covered landscape with church for the winter and a leafy tree flanked cottage by the water for summer.  I especially love the blue sky over black church in winter, which has an almost electric feeling about it.  Found in Pennsylvania, late 19th c or so, I believe, with mellow gold paint on the wood of the frame.

8 3/8" x  6 3/8" x 5/16". Paintings in very good condition. One small loss to the frame at lower left corner visible on the "winter" side, I don't think detracting. Very stable and sound, with an old string for hanging. Signed on both sides.