Spread the sheet on a hard surface. Lay the wheat out on the sheet in a layer no more than a foot thick.
Swing the flail so that the lower piece lands flat as it strikes the wheat. Use a large circular movement, swinging from back to front so the threshing end can build up some momentum before striking.
Flail for a few minutes. Check the wheat. As the wheat separates from the straw, remove the straw from the sheet.
Add more wheat to the sheet. Continue to flail. When you finish, remove all the straw from the sheet.
Use the sheet to pour the threshed wheat into a container for winnowing.
Grasp a handful of wheat by the stem end.
Bang the wheat against the inside walls of a clean metal garbage can. Use enough force to knock the wheat kernels off the stems. The force will also knock the chaff off the wheat.
Pour the wheat into a another container as it accumulates.
Spread the unthreshed wheat on a clean sheet.
Trample the wheat. You can drive animals like sheep or oxen over the wheat, or you can walk or dance on it yourself.
As the wheat falls off the stems, remove the stems and add more unthreshed wheat.