diff --git a/src/main/java/com/bthsrobotics/motorsim/robot/Robot.java b/src/main/java/com/bthsrobotics/motorsim/robot/Robot.java
index c21443a..34897d2 100644
--- a/src/main/java/com/bthsrobotics/motorsim/robot/Robot.java
+++ b/src/main/java/com/bthsrobotics/motorsim/robot/Robot.java
@@ -26,9 +26,12 @@ public Robot() {
     // This method will be called once every 20ms
     public void periodic() {
         motor.getFrame().setMarkerPosition(reference);
-        
+
+        // CODE HERE
+        // create error and deltaError variables
         double error = reference - motor.getPosition();
-        double deltaError = (error - prevError) / period;
+        double deltaError = error - prevError;
+        // CODE HERE
 
         prevError = error;
 
@@ -38,8 +41,10 @@ public void periodic() {
             hasMeasurement = true;
         }
 
-        double pid = kP * error + kD * deltaError;
-
-        motor.setVolts(pid);
+        // CODE HERE
+        // calculate input variable, setVolts
+        double input = kP * error + kD * (deltaError / period);
+        motor.setVolts(input);
+        // CODE HERE
     }
 }
diff --git a/target/classes/com/bthsrobotics/motorsim/robot/Robot.class b/target/classes/com/bthsrobotics/motorsim/robot/Robot.class
index ed2d067..68905a6 100644
Binary files a/target/classes/com/bthsrobotics/motorsim/robot/Robot.class and b/target/classes/com/bthsrobotics/motorsim/robot/Robot.class differ