Grandpa is using a winnowing basket to separate the grain from the chaff.
Tips
culture
Children's fingerprints are folk-classified as 箕 (a 'basket,' an open loop) or 斗 (a 'dipper,' a closed whorl). The rhyme 'one bucket poor, two buckets rich' is a popular fortune-telling game.
Bamboo cap on top, the head-form of 竹. It marks objects woven from bamboo strips - a winnowing basket was traditionally plaited bamboo. Same family as 篮 basket, 筐 hamper, 筷 chopsticks.
Bottom 其 is actually the original drawing of a winnowing basket; when it was borrowed away to be a pronoun, the bamboo cap was added on top to keep the basket meaning. It now also lends a near-rhyme sound (qí to jī).
