This is a simple question that can be expanded to make it a more meaningful question. When you ask this question to your children be prepared to listen and work the question to get a conversation going. Be prepared to ask additional questions to get beyond the "fine" or "okay" answers. Be prepared to share your day and use it as an opportunity to teach your children.
The asking of the question "How was your day?" is a parenting strategy. If you think about how you can make this experience with your children better, then will get much more from this question.
We have expanded on this strategy and many more in the book, "Strategies for Parenting: The Road to Independence."
Enjoy the video below as it will bring some insight into the need for "strategies for parenting" and how you can begin to think differently about parenting and impact your children. In the context of a gift, this would be an gift idea to a parent, to yourself as a parent and for children to benefit from improved parenting.