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