Update assignment to include order parameter implementation for Couzin model

Author: Daniel Precioso, PhD

modules/collective-motion/assignment.qmd

@@ -14,14 +14,15 @@ You can follow the guide here:
 
 1. Implement the Couzin rules and motion.
 2. Implement an animation that shows the individuals moving. You can see an example in the [Vicsek animation](vicsek-animation.qmd){.btn .btn-primary} chapter.
-3. Explore the parameter space and report your insights. Find the four collective dynamical behaviours described in the original paper [@couzin2002collective].
+3. Implement an order parameter that quantifies the degree of alignment in the system. Read the original paper [@couzin2002collective] to find out how they defined it. You can also check the [Vicsek order parameter](vicsek.qmd#order-parameter) for inspiration.
+4. Explore the parameter space and report your insights. Find the four collective dynamical behaviours described in the original paper [@couzin2002collective].
 
 Upload the code and a short report (1-2 pages done in LaTeX) describing your findings to the course platform.
 
 ## Extra Mile (Optional)
 
-- Add sliders to allow change parameters (of your choice) on real time
-- Implement the model in 3D, following the original paper [@couzin2002collective]
+- Add sliders to allow change parameters (of your choice) on real time.
+- Implement the model in 3D, following the original paper [@couzin2002collective].
 
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