Final answer:
Children's tendency to develop a mental pattern for being male or female can best be explained by gender schema theory.
Step-by-step explanation:
The tendency of children to develop a mental pattern for being male or female in much the same way they develop other concepts, such as 'dog,' 'bird,' and 'big,' can best be explained by gender schema theory. Gender schema theory suggests that children internalize societal expectations and learn gender roles by actively organizing and categorizing information about gender in their minds. They develop mental frameworks, or schemas, that guide their understanding and behavior related to gender.