Final answer:
Children learn to change their speech style to suit their situation around the age of 5 to 6 years, as their vocabulary and theory-of-mind skills become more advanced.
Step-by-step explanation:
At about what age do children learn to change their speech style to suit their situation? The answer is typically around 5 to 6 years of age. By this stage, children have developed a significant vocabulary and are capable of using language in more complex ways. They can engage in conversations, tell jokes, and begin to understand the concept of altering speech style according to social cues and settings. Children in this age group can also identify letters, words, and start learning to read and write. This is a reflection of the cognitive and psychosocial development that children undergo in which they can consider the perspectives of others, indicative of a theory-of-mind skill set.