🪜 Step-by-Step (continued)

Step 4: Add a flag couple (filled circle)

"Boil water" should also return a ready flag ↑ (True/False: is the water boiled?). This is a control signal, so it gets a filled circle. The parent uses this flag to decide whether to continue.

Step 5: Add conditional (diamond) and loop (curved arrow)

"Mix and serve" should only run if the water is ready (conditional — diamond on its line). "Get ingredients" might need to run repeatedly until all ingredients are found (loop — curved arrow).

🎯 Summary of Steps

Step	Action	Symbol Used
1	Identify main module → top rectangle	Rectangle
2	Break into sub-modules → child rectangles + lines	Rectangles + lines
3	Add data passing → open circles with arrows	Open circle (↑ or ↓)
4	Add flags/control → filled circles with arrows	Filled circle (↑ or ↓)
5	Add conditions and loops	Diamond + curved arrow