For the most part, this practice worked. Though I must admit, in times of desperation I gave Kathryn the contents of the whole box. Eventually you'll need alternatives to keep toddlers out of trouble. In that case, try one of the ideas listed below. They're safe, edible, nutritious, and provide multiple colors in every box.
Most cookie sheets are magnetic and can entertain for hours.
Provide your child with a cookie sheet and a variety of large, child-safe magnets, then sit back and let them play. Challenge them to drop the pins in the jug. For added fun, clothespins can be decorated to look like various people or animals. In warm weather, hold school outside. Encourage younger siblings to paint the house or sidewalk with water.