Note to parents: You can use a cardboard box or old desk as the shop, and empty packages and cartons from around the house for the items for sale. Get your kids ...

Dan Finkel runs Math for Love with his wife, Katherine Cook. They have developed two games: Tiny Polka Dot: A math-enriched card deck for 3- to 8-year-olds. “It’s really flexible,” Finkel said. You ...