3 years & up. Develop early mathematical skills with this set. The Ladybug Stones are durable and weatherproof, they can be used to explore counting to 20, odd and even numbers, and addition and subtraction. Each set includes two each of 0-10 (22 ladybugs), an activity guide, and set of 16 activity cards. The activity cards feature detailed, photographic images that will inspire children to explore early math skills such as matching, counting, ordering, even and odd numbers, and bonds/pairs. The cards are made from durable plastic and are tough enough to use in an outdoor area. Cards measure 8" x 11" each. Available separately or as a set.