The four volumes of the Factor Kinder series, a creative thinking textbook for children ages 6-7, are comprised of A Measurement and Numbers, B Puzzles and Geometry, C Operations and Space, and D Rules and Problem Solving.
The Factor Kinder series is a creative thinking mathematics textbook designed to go beyond the simple number learning and number play level for children under the age of 6, and to help children learn basic mathematical concepts through various thinking activities and develop their thinking skills.