Peaches and plums are drupes. Drupes have one seed enclosed in a hard case surrounded by flesh. Apples and pears are pomes. Pomes have several seeds enclosed in a core surrounded by flesh. Different kinds of plants form different amounts of seeds.
Some plants form only a few seeds, while others form many seeds.
The fruit is the part of a flowering plant that contains seeds. Help them observe and identify the placement of the seeds in each piece of fruit. Then have students group the fruits according to how the seeds are enclosed. You may wish to introduce the words berry, drupe, and pome to your students. If so, explain that many fruits commonly called berries are not berries according to the scientific definition.