diff --git a/sky/packages/sky/lib/src/animation/animated_value.dart b/sky/packages/sky/lib/src/animation/animated_value.dart
index f5854f46906..ff1fba65046 100644
--- a/sky/packages/sky/lib/src/animation/animated_value.dart
+++ b/sky/packages/sky/lib/src/animation/animated_value.dart
@@ -77,8 +77,8 @@ class AnimationTiming {
 
 /// An animated variable with a concrete type
 class AnimatedValue<T extends dynamic> extends AnimationTiming implements AnimatedVariable {
-  AnimatedValue(this.begin, { this.end, Interval interval, Curve curve, Curve reverseCurve })
-    : super(interval: interval, curve: curve, reverseCurve: reverseCurve) {
+  AnimatedValue(this.begin, { this.end, Interval interval, Interval reverseInterval, Curve curve, Curve reverseCurve })
+    : super(interval: interval, reverseInterval: reverseInterval, curve: curve, reverseCurve: reverseCurve) {
     value = begin;
   }
 
@@ -110,8 +110,8 @@ class AnimatedList extends AnimationTiming implements AnimatedVariable {
   /// The list of variables contained in the list
   List<AnimatedVariable> variables;
 
-  AnimatedList(this.variables, { Interval interval, Curve curve, Curve reverseCurve })
-    : super(interval: interval, curve: curve, reverseCurve: reverseCurve);
+  AnimatedList(this.variables, { Interval interval, Interval reverseInterval, Curve curve, Curve reverseCurve })
+    : super(interval: interval, reverseInterval: reverseInterval, curve: curve, reverseCurve: reverseCurve);
 
   // Updates the value of all the variables in the list according to the given animation clock value and direction
   void setProgress(double t, Direction direction) {
@@ -128,8 +128,8 @@ class AnimatedList extends AnimationTiming implements AnimatedVariable {
 /// This class specializes the interpolation of AnimatedValue<Color> to be
 /// appropriate for colors.
 class AnimatedColorValue extends AnimatedValue<Color> {
-  AnimatedColorValue(Color begin, { Color end, Curve curve })
-    : super(begin, end: end, curve: curve);
+  AnimatedColorValue(Color begin, { Color end, Interval interval, Interval reverseInterval, Curve curve, Curve reverseCurve })
+    : super(begin, end: end, interval: interval, reverseInterval: reverseInterval, curve: curve, reverseCurve: reverseCurve);
 
   Color lerp(double t) => Color.lerp(begin, end, t);
 }
@@ -139,8 +139,8 @@ class AnimatedColorValue extends AnimatedValue<Color> {
 /// This class specializes the interpolation of AnimatedValue<Rect> to be
 /// appropriate for rectangles.
 class AnimatedRect extends AnimatedValue<Rect> {
-  AnimatedRect(Rect begin, { Rect end, Curve curve })
-    : super(begin, end: end, curve: curve);
+  AnimatedRect(Rect begin, { Rect end, Interval interval, Interval reverseInterval, Curve curve, Curve reverseCurve })
+    : super(begin, end: end, interval: interval, reverseInterval: reverseInterval, curve: curve, reverseCurve: reverseCurve);
 
   Rect lerp(double t) => Rect.lerp(begin, end, t);
 }
diff --git a/sky/packages/sky/lib/src/animation/animation_performance.dart b/sky/packages/sky/lib/src/animation/animation_performance.dart
index 92046edd4b2..d862f7e1f2c 100644
--- a/sky/packages/sky/lib/src/animation/animation_performance.dart
+++ b/sky/packages/sky/lib/src/animation/animation_performance.dart
@@ -32,7 +32,7 @@ enum AnimationStatus {
 /// [fling] the timeline causing a physics-based simulation to take over the
 /// progression.
 class AnimationPerformance {
-  AnimationPerformance({AnimatedVariable variable, this.duration}) :
+  AnimationPerformance({ AnimatedVariable variable, this.duration }) :
     _variable = variable {
     _timeline = new Timeline(_tick);
   }
@@ -68,7 +68,8 @@ class AnimationPerformance {
     if (variable == null) {
       variable = newVariable;
     } else if (variable is AnimatedList) {
-      (variable as AnimatedList).variables.add(newVariable);
+      final AnimatedList variable = this.variable; // TODO(ianh): Remove this line when the analyzer is cleverer
+      variable.variables.add(newVariable);
     } else {
       variable = new AnimatedList([variable, newVariable]);
     }
@@ -219,7 +220,7 @@ class AnimationPerformance {
 
 /// An animation performance with an animated variable with a concrete type
 class ValueAnimation<T> extends AnimationPerformance {
-  ValueAnimation({AnimatedValue<T> variable, Duration duration}) :
+  ValueAnimation({ AnimatedValue<T> variable, Duration duration }) :
     super(variable: variable, duration: duration);
 
   AnimatedValue<T> get variable => _variable as AnimatedValue<T>;
diff --git a/sky/packages/sky/lib/src/animation/curves.dart b/sky/packages/sky/lib/src/animation/curves.dart
index d7dd325efdb..791f45bcc14 100644
--- a/sky/packages/sky/lib/src/animation/curves.dart
+++ b/sky/packages/sky/lib/src/animation/curves.dart
@@ -21,23 +21,14 @@ abstract class Curve {
   double transform(double t);
 }
 
-/// The idenity map over the unit interval
+/// The identity map over the unit interval
 class Linear implements Curve {
   const Linear();
-
-  double transform(double t) {
-    return t;
-  }
+  double transform(double t) => t;
 }
 
 /// A curve that is initially 0.0, then linear, then 1.0
 class Interval implements Curve {
-  /// The smallest value for which this interval is 0.0
-  final double start;
-
-  /// The smallest value for which this interval is 1.0
-  final double end;
-
   Interval(this.start, this.end) {
     assert(start >= 0.0);
     assert(start <= 1.0);
@@ -45,6 +36,12 @@ class Interval implements Curve {
     assert(end <= 1.0);
   }
 
+  /// The smallest value for which this interval is 0.0
+  final double start;
+
+  /// The smallest value for which this interval is 1.0
+  final double end;
+
   double transform(double t) {
     return ((t - start) / (end - start)).clamp(0.0, 1.0);
   }
@@ -52,23 +49,21 @@ class Interval implements Curve {
 
 /// A cubic polynomial mapping of the unit interval
 class Cubic implements Curve {
+  const Cubic(this.a, this.b, this.c, this.d);
+
   final double a;
   final double b;
   final double c;
   final double d;
 
-  const Cubic(this.a, this.b, this.c, this.d);
-
   double transform(double t) {
     double start = 0.0;
     double end = 1.0;
     while (true) {
       double midpoint = (start + end) / 2;
       double estimate = _evaluateCubic(a, c, midpoint);
-
       if ((t - estimate).abs() < _kCubicErrorBound)
         return _evaluateCubic(b, d, midpoint);
-
       if (estimate < t)
         start = midpoint;
       else
@@ -94,7 +89,6 @@ double _bounce(double t) {
 /// An oscillating curve that grows in magnitude
 class BounceInCurve implements Curve {
   const BounceInCurve();
-
   double transform(double t) {
     return 1.0 - _bounce(1.0 - t);
   }
@@ -103,7 +97,6 @@ class BounceInCurve implements Curve {
 /// An oscillating curve that shrink in magnitude
 class BounceOutCurve implements Curve {
   const BounceOutCurve();
-
   double transform(double t) {
     return _bounce(t);
   }
@@ -112,7 +105,6 @@ class BounceOutCurve implements Curve {
 /// An oscillating curve that first grows and then shrink in magnitude
 class BounceInOutCurve implements Curve {
   const BounceInOutCurve();
-
   double transform(double t) {
     if (t < 0.5)
       return (1.0 - _bounce(1.0 - t)) * 0.5;
@@ -125,7 +117,6 @@ class BounceInOutCurve implements Curve {
 class ElasticInCurve implements Curve {
   const ElasticInCurve([this.period = 0.4]);
   final double period;
-
   double transform(double t) {
     double s = period / 4.0;
     t = t - 1.0;
@@ -137,7 +128,6 @@ class ElasticInCurve implements Curve {
 class ElasticOutCurve implements Curve {
   const ElasticOutCurve([this.period = 0.4]);
   final double period;
-
   double transform(double t) {
     double s = period / 4.0;
     return math.pow(2.0, -10 * t) * math.sin((t - s) * (math.PI * 2.0) / period) + 1.0;
@@ -148,7 +138,6 @@ class ElasticOutCurve implements Curve {
 class ElasticInOutCurve implements Curve {
   const ElasticInOutCurve([this.period = 0.4]);
   final double period;
-
   double transform(double t) {
     double s = period / 4.0;
     t = 2.0 * t - 1.0;