diff --git a/18-project-bouncing-ball/01-draw-the-board/main.go b/18-project-bouncing-ball/01-draw-the-board/main.go
index c0980c8..2625b52 100644
--- a/18-project-bouncing-ball/01-draw-the-board/main.go
+++ b/18-project-bouncing-ball/01-draw-the-board/main.go
@@ -24,8 +24,8 @@ func main() {
 
 	// create the board
 	board := make([][]bool, width)
-	for row := range board {
-		board[row] = make([]bool, height)
+	for column := range board {
+		board[column] = make([]bool, height)
 	}
 
 	// draw a smiley
diff --git a/18-project-bouncing-ball/02-add-a-buffer/main.go b/18-project-bouncing-ball/02-add-a-buffer/main.go
index 2da18e7..5f157b1 100644
--- a/18-project-bouncing-ball/02-add-a-buffer/main.go
+++ b/18-project-bouncing-ball/02-add-a-buffer/main.go
@@ -24,8 +24,8 @@ func main() {
 
 	// create the board
 	board := make([][]bool, width)
-	for row := range board {
-		board[row] = make([]bool, height)
+	for column := range board {
+		board[column] = make([]bool, height)
 	}
 
 	// create a drawing buffer
diff --git a/18-project-bouncing-ball/03-animate/main.go b/18-project-bouncing-ball/03-animate/main.go
index eabfd32..dc48fe5 100644
--- a/18-project-bouncing-ball/03-animate/main.go
+++ b/18-project-bouncing-ball/03-animate/main.go
@@ -35,8 +35,8 @@ func main() {
 
 	// create the board
 	board := make([][]bool, width)
-	for row := range board {
-		board[row] = make([]bool, height)
+	for column := range board {
+		board[column] = make([]bool, height)
 	}
 
 	// create a drawing buffer
diff --git a/18-project-bouncing-ball/exercises/01-width-and-height/main.go b/18-project-bouncing-ball/exercises/01-width-and-height/main.go
index af2f8d3..a130187 100644
--- a/18-project-bouncing-ball/exercises/01-width-and-height/main.go
+++ b/18-project-bouncing-ball/exercises/01-width-and-height/main.go
@@ -118,8 +118,8 @@ func main() {
 
 	// create the board
 	board := make([][]bool, width)
-	for row := range board {
-		board[row] = make([]bool, height)
+	for column := range board {
+		board[column] = make([]bool, height)
 	}
 
 	// create a drawing buffer
diff --git a/18-project-bouncing-ball/exercises/01-width-and-height/solution/main.go b/18-project-bouncing-ball/exercises/01-width-and-height/solution/main.go
index 246c9ba..475049d 100644
--- a/18-project-bouncing-ball/exercises/01-width-and-height/solution/main.go
+++ b/18-project-bouncing-ball/exercises/01-width-and-height/solution/main.go
@@ -53,8 +53,8 @@ func main() {
 
 	// create the board
 	board := make([][]bool, width)
-	for row := range board {
-		board[row] = make([]bool, height)
+	for column := range board {
+		board[column] = make([]bool, height)
 	}
 
 	// create a drawing buffer
diff --git a/18-project-bouncing-ball/exercises/02-previous-positions/main.go b/18-project-bouncing-ball/exercises/02-previous-positions/main.go
index d912c40..810e48d 100644
--- a/18-project-bouncing-ball/exercises/02-previous-positions/main.go
+++ b/18-project-bouncing-ball/exercises/02-previous-positions/main.go
@@ -68,8 +68,8 @@ func main() {
 
 	// create the board
 	board := make([][]bool, width)
-	for row := range board {
-		board[row] = make([]bool, height)
+	for column := range board {
+		board[column] = make([]bool, height)
 	}
 
 	// create a drawing buffer
diff --git a/18-project-bouncing-ball/exercises/02-previous-positions/solution/main.go b/18-project-bouncing-ball/exercises/02-previous-positions/solution/main.go
index afe83b4..456ae4c 100644
--- a/18-project-bouncing-ball/exercises/02-previous-positions/solution/main.go
+++ b/18-project-bouncing-ball/exercises/02-previous-positions/solution/main.go
@@ -46,8 +46,8 @@ func main() {
 
 	// create the board
 	board := make([][]bool, width)
-	for row := range board {
-		board[row] = make([]bool, height)
+	for column := range board {
+		board[column] = make([]bool, height)
 	}
 
 	// create a drawing buffer
diff --git a/18-project-bouncing-ball/exercises/03-single-dimensional/main.go b/18-project-bouncing-ball/exercises/03-single-dimensional/main.go
index bd5e60b..abc900e 100644
--- a/18-project-bouncing-ball/exercises/03-single-dimensional/main.go
+++ b/18-project-bouncing-ball/exercises/03-single-dimensional/main.go
@@ -66,8 +66,8 @@ func main() {
 
 	// create the board
 	board := make([][]bool, width)
-	for row := range board {
-		board[row] = make([]bool, height)
+	for column := range board {
+		board[column] = make([]bool, height)
 	}
 
 	// create a drawing buffer