Draw what you are studying, what is around it, and what passes between them.
Before changing something, be clear about what you are looking at. Draw it together with the people and things around it.
Draw a boundary around the part you want to study. Engineers call this the system of interest. Show what is inside and what is outside.
Add arrows for what enters and leaves. These are inputs and outputs, such as food, electricity, money, or information. Name each arrow and show its direction.
A simple example
Draw a school kitchen and put a boundary around its staff, equipment, and cooking work. Put food suppliers, the electric company, the school office, students, and waste collection outside.
Ingredients, electricity, meal counts, and funding enter. Meals, waste, and supplier payments leave. The diagram shows how the kitchen connects to the world around it.
Context diagram: school kitchen
Wider context: school meal service. The highlighted boundary encloses the system of interest.
Food supplier
Ingredients
Payment
Electric utility
Electricity
School office
Meal counts and funding
SYSTEM BOUNDARY
School kitchen
System of interest
Staff
Equipment
Food-preparation processes
Meals
Students
Waste
Waste collection
Arrows point in the direction of each exchange. Ingredients, electricity, meal counts, and funding are inputs; meals, waste, and payment are outputs. The connecting relationships identify the interfaces. This teaching diagram shows selected exchanges; a working definition must identify all relevant interfaces.
From this perspective, reliable supplies and enough funding are desirable because the kitchen needs them to serve students on time. The kitchen must also stay within its budget.
Principles
Define the system boundary and its dependencies before trying to change it.
Moving a cost outside your boundary does not make that cost disappear.
Why this matters
We must draw the system boundary before proposing a change.
Identify what is inside, what is outside, and the inputs and outputs connecting them so everyone is examining the same system.
Learn more & discuss
More detail
Begin with the wider system context: the people, organizations, other systems, and environmental conditions relevant to the concern. Draw a context diagram showing the important elements and how they interact.
Identify the system of interest (SoI): the system you are studying, designing, or changing. State its purpose, then highlight it and draw a clear system boundary. Name what is inside and what remains outside in its environment.
Examine every interaction that crosses the boundary. The connection between elements is an interface; what passes across it is an input or an output relative to the system of interest. Label both the direction and the exchange: materials, energy, information, money, or other relevant flows. Where exchanges occur in both directions, show both.
The boundary establishes the scope of the analysis. External elements still matter because they supply inputs, receive outputs, or impose conditions and constraints. Review the context, boundary, and interfaces with the relevant stakeholders before analyzing changes.
Consider a school kitchen. The wider context includes food suppliers, the electric utility, the school office, students, and waste collection.
Choose the kitchen as the system of interest. Include its staff, equipment, and food-preparation processes inside the highlighted boundary. Keep the suppliers, utility, school office, students, and waste service outside it.
Ingredients and electricity enter the kitchen. The school office supplies meal counts and funding. Meals, waste, and supplier payments leave. Each arrow crossing the kitchen boundary must be named and its direction made clear.
A proposal to serve more meals must account for those interfaces: more ingredients, sufficient power and equipment capacity, accurate meal counts, funding, and waste removal. The kitchen cannot be understood by looking only at the cooking equipment.
Discussion questions
For individual reflection or classroom discussion. These questions are not graded.
What is the system of interest, and what purpose are you studying?
Draw the wider context, highlight the boundary, and identify what remains outside.
Name each interface and the direction, quantity, and timing of its inputs and outputs.
How would changing the boundary change your conclusion about resource use?