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