A math walk, or math trail, is a type of themed walk in the US, where direct experience is translated into the language of mathematics or abstract mathematical sciences such as information science, computer science, decision science, or probability and statistics. Some sources specify how to create a math walk whereas others define a math walk at a specific location such as a junior high school or in Boston. The journal The Mathematics Teacher includes a special section titled "Mathematical Lens" in many issues with the metaphor of lens capturing seeing the world as mathematics. Informal learning The idea that "math is everywhere", which is emphasized on a math walk, is captured by the philosophy of mathematicism with its early adherents, Pythagoras and Plato. The math walk also implicitly involves experiencing math via modeling since mathematics serves to model what we sense. The math walk is a form of informal learning, often in an outside environment or in a museum. This type of learning is contrasted with formal learning, which tends to be more structured and performed in a classroom. Maps and object discovery There are different approaches to designing a math walk. The walk can be guided or unguided. In a guided walk, the learners are guided by a person knowledgeable in the topic of mathematics. In an unguided walk, learners are provided with a map. The map identifies walking stops and identifiers, such as QR codes or bluetooth beacons, to provide additional information on how the objects experienced during a math walk are translated into mathematical language. Example math walk scene A walk can involve translation only, or translation and problem solving. For example, considering a window on a building involves first perceiving the window. After perception, there is a translation of the form of the window to mathematical language, such as the array where is the window's width and is the window's length. The array is a mathematical model of the window. This modeling is pure translation, without explicit problem solving. Questions such as "what is the area of the window?" require not only translation, but also the problem of solving for area: . A photo of the railroad tracks in Fernandina Beach Historic District captures a stop on a math walk. The walk's information can focus on discrete items. These items reflect counting and number sense. Examples of discrete items are the cloud structures, the distant