These thematic pictures of आकार और रंग are analogous to a visual dictionary. The theme "आकार और रंग" splits into several parts. For children, especially toddlers from 1 to 5 years old, it is better to divide the sets of cards over several days, or even weeks, so the information is absorbed better. Especially it is true if you are using flashcards to learn the hindi language, which is not your native language.
To expand your hindi language vocabulary on the "आकार और रंग" topic, flashcards games are the best way: