This report presents Qualitative Process theory (QP), a framework for reasoning about physical processes in common sense reasoning. QP provides a qualitative representation of quantities and processes, enabling the understanding of how processes occur, their effects, and when they stop. The theory is based on the idea that physical processes can be modeled using qualitative relationships between quantities, such as inequalities, and that these relationships can be used to reason about the behavior of objects and systems. QP theory is particularly useful for modeling physical phenomena such as motion, fluid flow, and material behavior. It allows for the prediction of future states, the interpretation of measurements, and the reasoning about causal relationships. The theory is implemented in a computer program called GIZMO, which uses QP to make predictions and interpret simple measurements. The theory is structured around the concepts of objects, quantities, and processes. Quantities are represented in a quantity space, which is a partial order of values that allows for qualitative reasoning. Processes are defined as changes that occur over time and are characterized by their effects on quantities. The theory also includes a notion of qualitative proportionality, which describes how quantities relate to each other in a qualitative manner. QP theory is applied to various examples, including modeling fluid flow, motion, and materials. These examples illustrate how the theory can be used to reason about physical phenomena and make predictions. The theory is also discussed in the context of other issues in common sense reasoning, such as causal reasoning and measurement interpretation. The report also describes the implementation of QP theory in GIZMO, which is a computer program that uses the theory to make predictions and interpret measurements. The representations and algorithms used in GIZMO are detailed, and the program is illustrated with several examples. Overall, QP theory provides a useful framework for reasoning about physical processes and is an important contribution to the field of artificial intelligence and common sense reasoning.This report presents Qualitative Process theory (QP), a framework for reasoning about physical processes in common sense reasoning. QP provides a qualitative representation of quantities and processes, enabling the understanding of how processes occur, their effects, and when they stop. The theory is based on the idea that physical processes can be modeled using qualitative relationships between quantities, such as inequalities, and that these relationships can be used to reason about the behavior of objects and systems. QP theory is particularly useful for modeling physical phenomena such as motion, fluid flow, and material behavior. It allows for the prediction of future states, the interpretation of measurements, and the reasoning about causal relationships. The theory is implemented in a computer program called GIZMO, which uses QP to make predictions and interpret simple measurements. The theory is structured around the concepts of objects, quantities, and processes. Quantities are represented in a quantity space, which is a partial order of values that allows for qualitative reasoning. Processes are defined as changes that occur over time and are characterized by their effects on quantities. The theory also includes a notion of qualitative proportionality, which describes how quantities relate to each other in a qualitative manner. QP theory is applied to various examples, including modeling fluid flow, motion, and materials. These examples illustrate how the theory can be used to reason about physical phenomena and make predictions. The theory is also discussed in the context of other issues in common sense reasoning, such as causal reasoning and measurement interpretation. The report also describes the implementation of QP theory in GIZMO, which is a computer program that uses the theory to make predictions and interpret measurements. The representations and algorithms used in GIZMO are detailed, and the program is illustrated with several examples. Overall, QP theory provides a useful framework for reasoning about physical processes and is an important contribution to the field of artificial intelligence and common sense reasoning.