diff --git a/day4/sketch_creature_behavior_colony/CircleCreature.pde b/day4/sketch_creature_behavior_colony/CircleCreature.pde
new file mode 100644
index 0000000..6e3f141
--- /dev/null
+++ b/day4/sketch_creature_behavior_colony/CircleCreature.pde
@@ -0,0 +1,18 @@
+class CircleCreature extends Creature {
+  
+  public CircleCreature(int x, int y, int r) {
+    super(x, y, r);
+    ellipseMode(RADIUS);
+  }  
+  
+  public void draw_shape(){
+    ellipse(0, 0, radius(), radius());  
+    line(0, 0, radius(), 0);
+  }
+  
+  public boolean inside(int mx, int my) {    
+    if(dist(mx, my, position().x, position().y) < radius()) return true;
+    return false;
+  }
+  
+};
diff --git a/day4/sketch_creature_behavior_colony/Colony.pde b/day4/sketch_creature_behavior_colony/Colony.pde
new file mode 100644
index 0000000..6ad3c1d
--- /dev/null
+++ b/day4/sketch_creature_behavior_colony/Colony.pde
@@ -0,0 +1,52 @@
+import teilchen.behavior.Arrival;
+
+class Colony {
+  
+  ArrayList<Colon> _colons = new ArrayList<Colon>(); 
+  Arrival _leader;
+  CollisionManager _collision;
+  
+  Physics _physics;
+  
+  public Colony(Physics p, CollisionManager c) {
+    _colons = new ArrayList<Colon>();
+    _leader = new Arrival();
+    _physics = p;
+    _collision = c;
+  }
+  
+  public void add(Creature c) {
+    
+    _physics.add(c);
+    _collision.collision().add(c);
+    
+    Colon colon = new Colon(c);
+    if(_colons.size() >= 1) {
+      colon.a.setPositionRef(_colons.get(_colons.size()-1).creature.position());
+    } else if(_colons.isEmpty()) {
+      colon.a.setPositionRef(_leader.position());
+    }
+    _colons.add(colon);
+  }
+  
+  public void migrate_to(int x, int y) {
+    _leader.position().set(x, y);
+  }
+  
+  public void remove(Creature c) {
+    // todo
+  }
+  
+  class Colon {    
+    Creature creature;
+    Arrival a;    
+    public Colon(Creature colon) {
+      creature = colon;
+      a = new Arrival();
+      a.breakforce(creature.radius() * 5);
+      a.breakradius(creature.radius() * 5);      
+      creature.behaviors().add(a);      
+    }        
+  }
+  
+}
diff --git a/day4/sketch_creature_behavior_colony/Creature.pde b/day4/sketch_creature_behavior_colony/Creature.pde
new file mode 100644
index 0000000..7f35285
--- /dev/null
+++ b/day4/sketch_creature_behavior_colony/Creature.pde
@@ -0,0 +1,37 @@
+import teilchen.BehaviorParticle;
+import mathematik.Vector3f;
+
+class Creature extends BehaviorParticle {
+  
+  float   _scale;
+  
+  public Creature(int x, int y, int r) {
+    super();
+    position().set(x, y);
+    maximumInnerForce(100);
+    radius(r);
+    _scale = 1.0;
+  }
+  
+  public void display() {
+    pushMatrix();
+    translate(position().x, position().y);
+    rotate(getRotation()); 
+    scale(_scale);
+    draw_shape();
+    popMatrix();
+    
+  }
+  
+  private float getRotation() {
+    if(velocity().isNaN() || velocity().magnitude() == 0) return 0;
+    Vector3f v = new Vector3f(-1, 0, 0);    
+    return velocity().angle(v);
+  }
+  
+  public void draw_shape() {}
+  
+  public boolean inside(int mx, int my){return false;}
+  
+};
+
diff --git a/day4/sketch_creature_behavior_colony/SquareCreature.pde b/day4/sketch_creature_behavior_colony/SquareCreature.pde
new file mode 100644
index 0000000..c218805
--- /dev/null
+++ b/day4/sketch_creature_behavior_colony/SquareCreature.pde
@@ -0,0 +1,22 @@
+class SquareCreature extends Creature {
+  
+  int _width;
+  int _height;
+  
+  public SquareCreature(int x, int y, int w, int h) {
+    super(x, y, (int)sqrt(pow(w / 2, 2) + pow(h / 2, 2)));
+    _width = w;
+    _height = h;    
+    rectMode(CENTER);
+  }  
+  
+  public void draw_shape(){
+    rect(0, 0, _width, _height);  
+  }
+  
+  public boolean inside(int mx, int my) {    
+    if(dist(mx, my, position().x, position().y) < radius()) return true;
+    return false;
+  }
+  
+};
diff --git a/day4/sketch_creature_behavior_colony/TriangleCreature.pde b/day4/sketch_creature_behavior_colony/TriangleCreature.pde
new file mode 100644
index 0000000..fc4e50b
--- /dev/null
+++ b/day4/sketch_creature_behavior_colony/TriangleCreature.pde
@@ -0,0 +1,36 @@
+class TriangleCreature extends Creature {
+  
+  PVector A, B, C;
+  
+  public TriangleCreature(int x, int y, int r) {
+    super(x, y, r);
+    
+    A = new PVector();
+    B = new PVector();
+    C = new PVector();
+    
+    float theta = TWO_PI/3;
+    
+    A.x = cos(0 * theta) * r;
+    A.y = sin(0 * theta) * r;
+    
+    B.x = cos(1 * theta) * r;
+    B.y = sin(1 * theta) * r;
+    
+    C.x = cos(2 * theta) * r;
+    C.y = sin(2 * theta) * r;
+    
+  }  
+  
+  public void draw_shape(){
+    triangle(A.x, A.y, B.x, B.y, C.x, C.y);  
+    line(0, 0, A.x, 0);
+  }
+  
+  public boolean inside(int mx, int my) {    
+    if(dist(mx, my, position().x, position().y) < radius()) return true;
+    return false;
+  }
+
+    
+};
diff --git a/day4/sketch_creature_behavior_colony/sketch.properties b/day4/sketch_creature_behavior_colony/sketch.properties
new file mode 100644
index 0000000..8630fa2
--- /dev/null
+++ b/day4/sketch_creature_behavior_colony/sketch.properties
@@ -0,0 +1,2 @@
+mode.id=processing.mode.java.JavaMode
+mode=Java
diff --git a/day4/sketch_creature_behavior_colony/sketch_creature_behavior_colony.pde b/day4/sketch_creature_behavior_colony/sketch_creature_behavior_colony.pde
new file mode 100644
index 0000000..8582202
--- /dev/null
+++ b/day4/sketch_creature_behavior_colony/sketch_creature_behavior_colony.pde
@@ -0,0 +1,60 @@
+import teilchen.Physics;
+import teilchen.util.CollisionManager;
+
+final int CANVAS_WIDTH = 500;
+final int CANVAS_HEIGHT = 500;
+
+Physics physics;
+
+CollisionManager collision;
+
+Colony colony;
+
+ArrayList<Creature> creatures = new ArrayList<Creature>();
+
+void setup() {  
+  size(CANVAS_WIDTH, CANVAS_HEIGHT);
+  background(23, 68, 250);
+  frameRate(30);
+  
+  physics = new Physics();
+  
+  collision = new CollisionManager();
+  collision.minimumDistance(25);
+  
+  colony = new Colony(physics, collision);  
+  
+}
+
+void draw() {
+  
+  colony.migrate_to(mouseX, mouseY);
+  
+  collision.createCollisionResolvers();
+  collision.loop(1.0 / frameRate);
+
+  physics.step(1.0 / frameRate);
+ 
+  background(23, 68, 250);
+  stroke(255);
+  noFill();
+  
+  for(int i = 0; i < creatures.size(); i++) {
+    Creature c = creatures.get(i);
+    c.display();
+  }
+  
+  collision.removeCollisionResolver();
+
+}
+
+void mousePressed() {
+  
+  Creature c = new CircleCreature(mouseX, mouseY, 10);
+  
+  creatures.add(c);
+  
+  colony.add(c);
+  
+}
+
diff --git a/day4/sketch_creature_behavior_herd/CircleCreature.pde b/day4/sketch_creature_behavior_herd/CircleCreature.pde
new file mode 100644
index 0000000..6e3f141
--- /dev/null
+++ b/day4/sketch_creature_behavior_herd/CircleCreature.pde
@@ -0,0 +1,18 @@
+class CircleCreature extends Creature {
+  
+  public CircleCreature(int x, int y, int r) {
+    super(x, y, r);
+    ellipseMode(RADIUS);
+  }  
+  
+  public void draw_shape(){
+    ellipse(0, 0, radius(), radius());  
+    line(0, 0, radius(), 0);
+  }
+  
+  public boolean inside(int mx, int my) {    
+    if(dist(mx, my, position().x, position().y) < radius()) return true;
+    return false;
+  }
+  
+};
diff --git a/day4/sketch_creature_behavior_herd/Creature.pde b/day4/sketch_creature_behavior_herd/Creature.pde
new file mode 100644
index 0000000..7f35285
--- /dev/null
+++ b/day4/sketch_creature_behavior_herd/Creature.pde
@@ -0,0 +1,37 @@
+import teilchen.BehaviorParticle;
+import mathematik.Vector3f;
+
+class Creature extends BehaviorParticle {
+  
+  float   _scale;
+  
+  public Creature(int x, int y, int r) {
+    super();
+    position().set(x, y);
+    maximumInnerForce(100);
+    radius(r);
+    _scale = 1.0;
+  }
+  
+  public void display() {
+    pushMatrix();
+    translate(position().x, position().y);
+    rotate(getRotation()); 
+    scale(_scale);
+    draw_shape();
+    popMatrix();
+    
+  }
+  
+  private float getRotation() {
+    if(velocity().isNaN() || velocity().magnitude() == 0) return 0;
+    Vector3f v = new Vector3f(-1, 0, 0);    
+    return velocity().angle(v);
+  }
+  
+  public void draw_shape() {}
+  
+  public boolean inside(int mx, int my){return false;}
+  
+};
+
diff --git a/day4/sketch_creature_behavior_herd/Herd.pde b/day4/sketch_creature_behavior_herd/Herd.pde
new file mode 100644
index 0000000..ba5c3a7
--- /dev/null
+++ b/day4/sketch_creature_behavior_herd/Herd.pde
@@ -0,0 +1,85 @@
+import teilchen.Physics;
+import teilchen.behavior.Alignment;
+import teilchen.behavior.Cohesion;
+import teilchen.behavior.Motor;
+import teilchen.behavior.Separation;
+import teilchen.behavior.Wander;
+import java.util.Vector;
+import teilchen.IBehaviorParticle;
+
+class Herd {
+  
+  ArrayList<Herderer> _herderers = new ArrayList<Herderer>(); 
+  Vector<Creature> _creatures = new Vector<Creature>();
+  CollisionManager _collision;
+  
+  Physics _physics;
+  
+  public Herd(Physics p, CollisionManager c) {
+    _herderers = new ArrayList<Herderer>();
+    _physics = p;
+    _collision = c;
+  }
+  
+  public void add(Creature c) {
+    
+    _physics.add(c);
+    _collision.collision().add(c);
+    _creatures.add(c);
+    
+    Herderer h = new Herderer(c);
+    _herderers.add(h);
+  }
+    
+  public void remove(Creature c) {
+    // todo
+  }
+  
+  public void update() {
+    for(int i = 0; i < _herderers.size(); i++) {
+      _herderers.get(i).update();
+    }
+  }  
+  
+  class Herderer {    
+    Creature creature;
+    Separation separation;
+    Alignment alignment;
+    Cohesion cohesion;
+    Wander wander;
+    Motor motor;
+    
+    public Herderer(Creature c) {
+             
+      creature = c;      
+      
+      separation = new Separation();
+      separation.proximity(10);
+      separation.weight(10.0f);
+      creature.behaviors().add(separation);
+      
+      cohesion = new Cohesion();
+      cohesion.proximity(500);
+      cohesion.weight(5.0f);
+      creature.behaviors().add(cohesion);
+      
+      wander = new Wander();
+      creature.behaviors().add(wander);
+      
+      /*
+      motor = new Motor();
+      motor.auto_update_direction(true);
+      motor.strength(0.01f);
+      creature.behaviors().add(motor);
+      */      
+      
+    }       
+   
+   public void update() {
+    separation.neighbors(_creatures);
+    cohesion.neighbors(_creatures);     
+   }
+   
+  }
+  
+}
diff --git a/day4/sketch_creature_behavior_herd/SquareCreature.pde b/day4/sketch_creature_behavior_herd/SquareCreature.pde
new file mode 100644
index 0000000..c218805
--- /dev/null
+++ b/day4/sketch_creature_behavior_herd/SquareCreature.pde
@@ -0,0 +1,22 @@
+class SquareCreature extends Creature {
+  
+  int _width;
+  int _height;
+  
+  public SquareCreature(int x, int y, int w, int h) {
+    super(x, y, (int)sqrt(pow(w / 2, 2) + pow(h / 2, 2)));
+    _width = w;
+    _height = h;    
+    rectMode(CENTER);
+  }  
+  
+  public void draw_shape(){
+    rect(0, 0, _width, _height);  
+  }
+  
+  public boolean inside(int mx, int my) {    
+    if(dist(mx, my, position().x, position().y) < radius()) return true;
+    return false;
+  }
+  
+};
diff --git a/day4/sketch_creature_behavior_herd/TriangleCreature.pde b/day4/sketch_creature_behavior_herd/TriangleCreature.pde
new file mode 100644
index 0000000..fc4e50b
--- /dev/null
+++ b/day4/sketch_creature_behavior_herd/TriangleCreature.pde
@@ -0,0 +1,36 @@
+class TriangleCreature extends Creature {
+  
+  PVector A, B, C;
+  
+  public TriangleCreature(int x, int y, int r) {
+    super(x, y, r);
+    
+    A = new PVector();
+    B = new PVector();
+    C = new PVector();
+    
+    float theta = TWO_PI/3;
+    
+    A.x = cos(0 * theta) * r;
+    A.y = sin(0 * theta) * r;
+    
+    B.x = cos(1 * theta) * r;
+    B.y = sin(1 * theta) * r;
+    
+    C.x = cos(2 * theta) * r;
+    C.y = sin(2 * theta) * r;
+    
+  }  
+  
+  public void draw_shape(){
+    triangle(A.x, A.y, B.x, B.y, C.x, C.y);  
+    line(0, 0, A.x, 0);
+  }
+  
+  public boolean inside(int mx, int my) {    
+    if(dist(mx, my, position().x, position().y) < radius()) return true;
+    return false;
+  }
+
+    
+};
diff --git a/day4/sketch_creature_behavior_herd/sketch.properties b/day4/sketch_creature_behavior_herd/sketch.properties
new file mode 100644
index 0000000..8630fa2
--- /dev/null
+++ b/day4/sketch_creature_behavior_herd/sketch.properties
@@ -0,0 +1,2 @@
+mode.id=processing.mode.java.JavaMode
+mode=Java
diff --git a/day4/sketch_creature_behavior_herd/sketch_creature_behavior_herd.pde b/day4/sketch_creature_behavior_herd/sketch_creature_behavior_herd.pde
new file mode 100644
index 0000000..062cd7a
--- /dev/null
+++ b/day4/sketch_creature_behavior_herd/sketch_creature_behavior_herd.pde
@@ -0,0 +1,60 @@
+import teilchen.Physics;
+import teilchen.util.CollisionManager;
+
+final int CANVAS_WIDTH = 500;
+final int CANVAS_HEIGHT = 500;
+
+Physics physics;
+
+CollisionManager collision;
+
+Herd herd;
+
+ArrayList<Creature> creatures = new ArrayList<Creature>();
+
+void setup() {  
+  size(CANVAS_WIDTH, CANVAS_HEIGHT);
+  background(23, 68, 250);
+  frameRate(30);
+  
+  physics = new Physics();
+  
+  collision = new CollisionManager();
+  collision.minimumDistance(25);  
+  
+  herd = new Herd(physics, collision);  
+  
+}
+
+void draw() {
+
+  collision.createCollisionResolvers();
+  collision.loop(1.0 / frameRate);
+  
+  physics.step(1.0 / frameRate);
+  
+  herd.update();
+ 
+  background(23, 68, 250);
+  stroke(255);
+  noFill();
+  
+  for(int i = 0; i < creatures.size(); i++) {
+    Creature c = creatures.get(i);
+    c.display();
+  }
+  
+  collision.removeCollisionResolver();
+
+}
+
+void mousePressed() {
+  
+  Creature c = new CircleCreature(mouseX, mouseY, 10);
+  
+  creatures.add(c);
+  
+  herd.add(c);
+  
+}
+