These thematic pictures of 色と形 are analogous to a visual dictionary. The theme "色と形" 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 japanese language, which is not your native language.
To expand your japanese language vocabulary on the "色と形" topic, flashcards games are the best way: