[Easy to Use] The sliding ruler for kids is easy to use by moving the ruler, selecting a number in the field and adding the circle up and down and easily calculate addition and subtraction by moving the board. [Smooth and Burr-Free] The smooth and burr-free math slider ruler is made of durable ABS material, designed with clear numbers to protect eyes and won't hurt fingers when of learning. [Mathematical Education] Help children solve addition and subtraction from 0 to 10, addition and subtraction toys help with math education, a learning aid fun math education. [Fun Educational Toy] The addition subtraction slider ruler arouses interest in math learning and is easier to learn in deep memory, so that kids don't get bored when learning. [Wide Range of Uses] Suitable for parents to guide their children, Ruler for Kids Learning is a useful teaching tool for teachers, ideal for kids. lessons at home and at school.