Provide Open-Ended Answers To Stimulate Thinking
At this stage, a lot of things around contribute to stimulating your child's thinking skills. When responding to your child’s query, try to provide open-ended answers so that the child can keep thinking and exploring in that direction. If you do not know the answer, say so to the child.
Take this as an opportunity to look through books and find the answer together. If you go about answering every query of your child in a conclusive manner, your child will not be intrigued to know further and that would hinder the progress of his thinking skills. So whenever responding to his queries, keep the answers open ended so as to encourage further questions and research on the part of the child. This will give him something to explore and learn further about. He may come with some interesting finds and surprise you too.
Besides, this practice will also raise your child into a person who does not rely on other people for answers but prefers to go and find them by himself. If there is a question even you do not know the answer to, then tell that to your child and applaud him for asking such an interesting question. Then use this chance to explore the answers with him together. This can also be a very good bonding time with your kid while the two of you also learn something new.