Abstract
Rules of thumb are simple instructions, used to guide actions toward a specific result, without need of advanced knowledge. Knowing adequate rules of thumb is a common form of technological knowledge. It differs both from science-based and intuitive (or tacit) technological knowledge, although it may have its origin in experience, scientific knowledge, trial and error, or a combination thereof. One of the major advantages of rules of thumb is the ease with which they can be learned. One of their major disadvantages is that they cannot easily be adjusted to new situations or conditions.