Models represent complex ideas and relationships in visual, spatial, and tactile ways.

- The ZYGO is the model for Big Little Thinking (BLT).
- To understand the ZYGO is to understand the frames, dimensions, and dynamics of BLT.
- To think through the ZYGO is to see the world through a window - a Big Little Window.

As a model, the ZYGO has two basic forms that represent different levels of understanding:

- The Simple ZYGO (sZ) of 'Big Little WINDOW' represents the core relationship of BLT between left-right and positive-negative.
- The Complex ZYGO (cZ) represents more diverse and differentiated relationships of BLT between all frames, dimensions, and dynamics.

Whilst both the simple and complex ZYGO are depicted by a round model, the BLT framework can be modelled in many different ways, including squares. Some alternative models are provided.

The Simple ZYGO is a 'window on the world' that can be understood and applied independently to explore a range of problems.

Specifically, the Simple ZYGO explores problems through four **panes **or perspectives on a pair. It combines two of BLT's four dimensions (Left-Right and Positive-Negative) to explore the most significant pairs (zygos) of a problem. Accordingly, the four panes are:

- Left-Positive
- Left Negative
- Right Positive
- Right Negative.

All zygos relevant to the problem can be explored through the four panes of the ZYGO. This exploration leads to (a) the realisation of relationships between different zygos, and (b) the realisation of the relevance of the other frames of BLT's more comprehensive model - the Complex ZYGO (cZ).

The ZYGO is usefully seen as a lens or window on the world. It is part window, part mirror. Consider the following quotes for inspiration:

- "The purpose of education is to turn windows into mirrors". (Sydney J. Harris)

- "Through all the windows I only see infinity". (Mark Z. Danielewski)

- "I live in a small house but my window looks out on a very large world". (Confucius)

- "My favourite journey is looking out the window". (Edward Gorey)