diff --git a/core/src/main/scala/spark/RDD.scala b/core/src/main/scala/spark/RDD.scala
index 7aa4b0a1735d52ea49ada97d7a998687883fbc05..5ce524c0e78541399c4be1a2011a660bc1104b5e 100644
--- a/core/src/main/scala/spark/RDD.scala
+++ b/core/src/main/scala/spark/RDD.scala
@@ -511,9 +511,9 @@ abstract class RDD[T: ClassManifest](@transient sc: SparkContext) extends Serial
   }
 
   /**
-   * Tuples the elements of this RDD by applying `f`.
+   * Creates tuples of the elements in this RDD by applying `f`.
    */
-  def tupleBy[K](f: T => K): RDD[(K, T)] = {
+  def keyBy[K](f: T => K): RDD[(K, T)] = {
     map(x => (f(x), x))
   }
 
diff --git a/core/src/test/scala/spark/RDDSuite.scala b/core/src/test/scala/spark/RDDSuite.scala
index 78328842244f72b11f2be8046b50440ab65d862a..77bff8aba13d15b656d8daf6f5a35769a52c6a6a 100644
--- a/core/src/test/scala/spark/RDDSuite.scala
+++ b/core/src/test/scala/spark/RDDSuite.scala
@@ -35,7 +35,7 @@ class RDDSuite extends FunSuite with BeforeAndAfter {
     assert(nums.flatMap(x => 1 to x).collect().toList === List(1, 1, 2, 1, 2, 3, 1, 2, 3, 4))
     assert(nums.union(nums).collect().toList === List(1, 2, 3, 4, 1, 2, 3, 4))
     assert(nums.glom().map(_.toList).collect().toList === List(List(1, 2), List(3, 4)))
-    assert(nums.tupleBy(_.toString).collect().toList === List(("1", 1), ("2", 2), ("3", 3), ("4", 4)))
+    assert(nums.keyBy(_.toString).collect().toList === List(("1", 1), ("2", 2), ("3", 3), ("4", 4)))
     val partitionSums = nums.mapPartitions(iter => Iterator(iter.reduceLeft(_ + _)))
     assert(partitionSums.collect().toList === List(3, 7))