Arlington County has an extensive network of bicycle infrastructure, including 50 miles of shared-use off-street trails. These multi-use trails are generally 10 feet wide with a solid yellow line striped down the middle to separate users.
Constructive mathematics. Idea. Broadly speaking, constructive mathematics is mathematics done without the principle of excluded middle (or other principles, such as the full axiom of choice, that imply it).
Manipulative (mathematics) In mathematics, a manipulative is an object which is designed so that a learner can perceive some mathematical concept by manipulating it, hence its name. The use of manipulatives provides a way for children to learn concepts through developmentally appropriate hands-on experience.