Use buttons with varying characteristics such as small, big, round, shaped, two holes, four holes and different colors. Set a piece of paper on a low table so all the children can see. Choose a big button then show and tell the kindergartners it can go on the paper. Choose a small button then show and tell the children it cannot go on the paper. Repeat these actions once more then ask them what the sorting rules are, repeat until the children guess that the rule is big buttons. Once they understand, move on to more challenging characteristics, such as, buttons with four holes, dull buttons, red buttons and round buttons until they have a good grasp of the game.
Assign natural objects found outside to each kindergartner. For example; Tim has sticks, Lisa has leaves, John has flowers and Mary has pebbles. Let the children go outside and collect their designated material. While still outside have each child sort their objects at their discretion. Let the children take turns classifying how they sorted. Next, ask the rest of the children how else the objects can be sorted and classified.
Kindergartners can take a while to catch on. Sometimes they misunderstand the sorting process and will separate the objects by more than one characteristic, such as one pile has white rocks, the other pile has black rocks. To make clear what the goal is, say "These rocks are (white). These rocks are not (white)." Have the children finish your sentences until they understand what you are trying to accomplish. Make the game fun by offering a great deal of praise when they get a classification correct.
While teaching kindergartners how to sort and classify, use the appropriate vocabulary associated with the objects. Tell the children you are going to classify the groups, categories and sets. Talk about how things are the same or if they are different. Use amounts such as fewer or more. Descriptive words, such as shorter, thicker, lighter and thinner can also be introduced at this time.