diff --git a/03-packages-and-scopes/exercises/02-scopes/solution/main.go b/03-packages-and-scopes/exercises/02-scopes/solution/main.go
index 3775d96..f4e46a4 100644
--- a/03-packages-and-scopes/exercises/02-scopes/solution/main.go
+++ b/03-packages-and-scopes/exercises/02-scopes/solution/main.go
@@ -15,10 +15,10 @@ func main() {
 	// and I can call `hello` function here.
 	//
 	// this is because, package-scoped names
-	//   are shared in the same package
+	// are shared in the same package
 	hello()
 
-	// but here, i can't access the fmt package without
+	// but here, I can't access the fmt package without
 	// importing it.
 	//
 	// this is because, it's in the printer.go's file scope.
diff --git a/10-constants/02-typeless-constants/02-typed-vs-typeless/04/main.go b/10-constants/02-typeless-constants/02-typed-vs-typeless/04/main.go
index 35bcf1c..afa6d8f 100644
--- a/10-constants/02-typeless-constants/02-typed-vs-typeless/04/main.go
+++ b/10-constants/02-typeless-constants/02-typed-vs-typeless/04/main.go
@@ -13,7 +13,7 @@ import "fmt"
 func main() {
 	const min = 42
 
-	// i've removed int from the below declaration
+	// I've removed int from the below declaration
 	// since, min's default type is int (you'll learn)
 	var i = min
 
diff --git a/11-if/exercises/03-arg-count/main.go b/11-if/exercises/03-arg-count/main.go
index 3640847..3efb505 100644
--- a/11-if/exercises/03-arg-count/main.go
+++ b/11-if/exercises/03-arg-count/main.go
@@ -25,7 +25,7 @@ package main
 //  go run main.go hi there
 //    There are two: "hi there"
 //
-//  go run main.go i wanna be a gopher
+//  go run main.go I wanna be a gopher
 //    There are 5 arguments
 // ---------------------------------------------------------
 
diff --git a/16-slices/14-copy/02-hacker-incident/main.go b/16-slices/14-copy/02-hacker-incident/main.go
index 22b1a84..953c091 100644
--- a/16-slices/14-copy/02-hacker-incident/main.go
+++ b/16-slices/14-copy/02-hacker-incident/main.go
@@ -41,7 +41,7 @@ func main() {
 	// saved := make([]float64, len(data))
 	// copy(saved, data)
 
-	// #9: clone a slice using append nil (i prefer this)
+	// #9: clone a slice using append nil (I prefer this)
 	// saved := append([]float64(nil), data...)
 
 	// data[0] = 0 // #8
diff --git a/16-slices/exercises/21-correct-the-lyric/main.go b/16-slices/exercises/21-correct-the-lyric/main.go
index 66104de..288fc44 100644
--- a/16-slices/exercises/21-correct-the-lyric/main.go
+++ b/16-slices/exercises/21-correct-the-lyric/main.go
@@ -22,29 +22,29 @@ import (
 //
 // CURRENT OUTPUT
 //
-//  [all my troubles seemed so far away oh i believe in yesterday now it looks as though they are here to stay]
+//  [all my troubles seemed so far away oh I believe in yesterday now it looks as though they are here to stay]
 //
 // EXPECTED OUTPUT
 //
-//  [yesterday all my troubles seemed so far away now it looks as though they are here to stay oh i believe in yesterday]
+//  [yesterday all my troubles seemed so far away now it looks as though they are here to stay oh I believe in yesterday]
 //
 //
 // STEPS
 //
 //  INITIAL SLICE:
-//    [all my troubles seemed so far away oh i believe in yesterday now it looks as though they are here to stay]
+//    [all my troubles seemed so far away oh I believe in yesterday now it looks as though they are here to stay]
 //
 //
 //  1. Prepend "yesterday" to the `lyric` slice.
 //
 //     RESULT SHOULD BE:
-//     [yesterday all my troubles seemed so far away oh i believe in yesterday now it looks as though they are here to stay]
+//     [yesterday all my troubles seemed so far away oh I believe in yesterday now it looks as though they are here to stay]
 //
 //
 //  2. Put the words to the correct positions in the `lyric` slice.
 //
 //     RESULT SHOULD BE:
-//     [yesterday all my troubles seemed so far away now it looks as though they are here to stay oh i believe in yesterday]
+//     [yesterday all my troubles seemed so far away now it looks as though they are here to stay oh I believe in yesterday]
 //
 //
 //  3. Print the `lyric` slice.
@@ -65,7 +65,7 @@ import (
 
 func main() {
 	// DON'T TOUCH THIS:
-	lyric := strings.Fields(`all my troubles seemed so far away oh i believe in yesterday now it looks as though they are here to stay`)
+	lyric := strings.Fields(`all my troubles seemed so far away oh I believe in yesterday now it looks as though they are here to stay`)
 
 	// ADD YOUR CODE BELOW:
 	// ...
diff --git a/16-slices/exercises/21-correct-the-lyric/solution/main.go b/16-slices/exercises/21-correct-the-lyric/solution/main.go
index 29ed4c6..1a6dd46 100644
--- a/16-slices/exercises/21-correct-the-lyric/solution/main.go
+++ b/16-slices/exercises/21-correct-the-lyric/solution/main.go
@@ -17,8 +17,8 @@ func main() {
 	// --- Correct Lyric ---
 	// yesterday all my troubles seemed so far away
 	// now it looks as though they are here to stay
-	// oh i believe in yesterday
-	lyric := strings.Fields(`all my troubles seemed so far away oh i believe in yesterday now it looks as though they are here to stay`)
+	// oh I believe in yesterday
+	lyric := strings.Fields(`all my troubles seemed so far away oh I believe in yesterday now it looks as though they are here to stay`)
 
 	// ------------------------------------------------------------------------
 	// #1: Prepend "yesterday" to `lyric`
@@ -26,10 +26,10 @@ func main() {
 
 	//
 	// --- BEFORE ---
-	// all my troubles seemed so far away oh i believe in yesterday
+	// all my troubles seemed so far away oh I believe in yesterday
 	//
 	// --- AFTER ---
-	// yesterday all my troubles seemed so far away oh i believe in yesterday
+	// yesterday all my troubles seemed so far away oh I believe in yesterday
 	//
 	// (warning: allocates a new backing array)
 	//
@@ -40,7 +40,7 @@ func main() {
 	// ------------------------------------------------------------------------
 
 	//
-	// yesterday all my troubles seemed so far away oh i believe in yesterday
+	// yesterday all my troubles seemed so far away oh I believe in yesterday
 	//                                              |               |
 	//                                              v               v
 	//                                       index: 8          pos: 13
@@ -49,10 +49,10 @@ func main() {
 
 	// --- BEFORE ---
 	//
-	// yesterday all my troubles seemed so far away oh i believe in yesterday now it looks as though they are here to stay
+	// yesterday all my troubles seemed so far away oh I believe in yesterday now it looks as though they are here to stay
 	//
 	// --- AFTER ---
-	// yesterday all my troubles seemed so far away oh i believe in yesterday now it looks as though they are here to stay oh i believe in yesterday
+	// yesterday all my troubles seemed so far away oh I believe in yesterday now it looks as though they are here to stay oh I believe in yesterday
 	//                                              ^
 	//
 	//                                              |
@@ -63,10 +63,10 @@ func main() {
 
 	//
 	// --- BEFORE ---
-	// yesterday all my troubles seemed so far away oh i believe in yesterday now it looks as though they are here to stay oh i believe in yesterday
+	// yesterday all my troubles seemed so far away oh I believe in yesterday now it looks as though they are here to stay oh I believe in yesterday
 	//
 	// --- AFTER ---
-	// yesterday all my troubles seemed so far away now it looks as though they are here to stay oh i believe in yesterday
+	// yesterday all my troubles seemed so far away now it looks as though they are here to stay oh I believe in yesterday
 	//
 	// (does not allocate a new backing array because cap(lyric[:N]) > M)
 	//
diff --git a/16-slices/exercises/25-add-lines/main.go b/16-slices/exercises/25-add-lines/main.go
index c1604ec..c664877 100644
--- a/16-slices/exercises/25-add-lines/main.go
+++ b/16-slices/exercises/25-add-lines/main.go
@@ -27,22 +27,22 @@ import (
 //
 // ORIGINAL SLICE:
 //
-//   [yesterday all my troubles seemed so far away now it looks as though they are here to stay oh i believe in yesterday]
+//   [yesterday all my troubles seemed so far away now it looks as though they are here to stay oh I believe in yesterday]
 //
 // EXPECTED SLICE (NEW):
 //
-//   [yesterday all my troubles seemed so far \n away now it looks as though they are here to stay \n oh i believe in yesterday \n]
+//   [yesterday all my troubles seemed so far \n away now it looks as though they are here to stay \n oh I believe in yesterday \n]
 //
 //
 // CURRENT OUTPUT
 //
-//  yesterday all my troubles seemed so far away now it looks as though they are here to stay oh i believe in yesterday
+//  yesterday all my troubles seemed so far away now it looks as though they are here to stay oh I believe in yesterday
 //
 // EXPECTED OUTPUT
 //
 //  yesterday all my troubles seemed so far away
 //  now it looks as though they are here to stay
-//  oh i believe in yesterday
+//  oh I believe in yesterday
 //
 //
 // RESTRICTIONS
@@ -72,7 +72,7 @@ import (
 func main() {
 	// You need to add a newline after each sentence in another slice.
 	// Don't touch the following code.
-	lyric := strings.Fields(`yesterday all my troubles seemed so far away now it looks as though they are here to stay oh i believe in yesterday`)
+	lyric := strings.Fields(`yesterday all my troubles seemed so far away now it looks as though they are here to stay oh I believe in yesterday`)
 
 	// ===================================
 	//
diff --git a/16-slices/exercises/25-add-lines/solution/main.go b/16-slices/exercises/25-add-lines/solution/main.go
index f80ad05..6dd15fe 100644
--- a/16-slices/exercises/25-add-lines/solution/main.go
+++ b/16-slices/exercises/25-add-lines/solution/main.go
@@ -16,7 +16,7 @@ import (
 )
 
 func main() {
-	lyric := strings.Fields(`yesterday all my troubles seemed so far away now it looks as though they are here to stay oh i believe in yesterday`)
+	lyric := strings.Fields(`yesterday all my troubles seemed so far away now it looks as though they are here to stay oh I believe in yesterday`)
 
 	// `+3` because we're going to add 3 newline characters to the fix slice.
 	fix := make([]string, len(lyric)+3)
@@ -34,7 +34,7 @@ func main() {
 	//
 	// + The second sentence has 10 words so its cutting index is 10.
 	//
-	//   now it looks as though they are here to stay oh i believe in yesterday
+	//   now it looks as though they are here to stay oh I believe in yesterday
 	//                                               |
 	//                                               v
 	//                                cutting index: 10
@@ -42,7 +42,7 @@ func main() {
 	//
 	// + The last sentence has 5 words so its cutting index is 5.
 	//
-	//   oh i believe in yesterday
+	//   oh I believe in yesterday
 	//                            |
 	//                            v
 	//             cutting index: 5
diff --git a/23-input-scanning/02-map-as-sets/shakespeare.txt b/23-input-scanning/02-map-as-sets/shakespeare.txt
index cd46cce..bff5be6 100644
--- a/23-input-scanning/02-map-as-sets/shakespeare.txt
+++ b/23-input-scanning/02-map-as-sets/shakespeare.txt
@@ -7,6 +7,6 @@ take him and cut him out in little stars
 and he will make the face of heaven so fine
 that all the world will be in love with night
 and pay no worship to the garish sun
-oh i have bought the mansion of love
-but not possessed it and though i am sold
-not yet enjoyed
\ No newline at end of file
+oh I have bought the mansion of love
+but not possessed it and though I am sold
+not yet enjoyed
diff --git a/23-input-scanning/exercises/01-uppercaser/shakespeare.txt b/23-input-scanning/exercises/01-uppercaser/shakespeare.txt
index cd46cce..bff5be6 100644
--- a/23-input-scanning/exercises/01-uppercaser/shakespeare.txt
+++ b/23-input-scanning/exercises/01-uppercaser/shakespeare.txt
@@ -7,6 +7,6 @@ take him and cut him out in little stars
 and he will make the face of heaven so fine
 that all the world will be in love with night
 and pay no worship to the garish sun
-oh i have bought the mansion of love
-but not possessed it and though i am sold
-not yet enjoyed
\ No newline at end of file
+oh I have bought the mansion of love
+but not possessed it and though I am sold
+not yet enjoyed
diff --git a/23-input-scanning/exercises/01-uppercaser/solution/shakespeare.txt b/23-input-scanning/exercises/01-uppercaser/solution/shakespeare.txt
index cd46cce..bff5be6 100644
--- a/23-input-scanning/exercises/01-uppercaser/solution/shakespeare.txt
+++ b/23-input-scanning/exercises/01-uppercaser/solution/shakespeare.txt
@@ -7,6 +7,6 @@ take him and cut him out in little stars
 and he will make the face of heaven so fine
 that all the world will be in love with night
 and pay no worship to the garish sun
-oh i have bought the mansion of love
-but not possessed it and though i am sold
-not yet enjoyed
\ No newline at end of file
+oh I have bought the mansion of love
+but not possessed it and though I am sold
+not yet enjoyed
diff --git a/23-input-scanning/exercises/02-unique-words/shakespeare.txt b/23-input-scanning/exercises/02-unique-words/shakespeare.txt
index cd46cce..bff5be6 100644
--- a/23-input-scanning/exercises/02-unique-words/shakespeare.txt
+++ b/23-input-scanning/exercises/02-unique-words/shakespeare.txt
@@ -7,6 +7,6 @@ take him and cut him out in little stars
 and he will make the face of heaven so fine
 that all the world will be in love with night
 and pay no worship to the garish sun
-oh i have bought the mansion of love
-but not possessed it and though i am sold
-not yet enjoyed
\ No newline at end of file
+oh I have bought the mansion of love
+but not possessed it and though I am sold
+not yet enjoyed
diff --git a/23-input-scanning/exercises/02-unique-words/solution/shakespeare.txt b/23-input-scanning/exercises/02-unique-words/solution/shakespeare.txt
index cd46cce..bff5be6 100644
--- a/23-input-scanning/exercises/02-unique-words/solution/shakespeare.txt
+++ b/23-input-scanning/exercises/02-unique-words/solution/shakespeare.txt
@@ -7,6 +7,6 @@ take him and cut him out in little stars
 and he will make the face of heaven so fine
 that all the world will be in love with night
 and pay no worship to the garish sun
-oh i have bought the mansion of love
-but not possessed it and though i am sold
-not yet enjoyed
\ No newline at end of file
+oh I have bought the mansion of love
+but not possessed it and though I am sold
+not yet enjoyed
diff --git a/23-input-scanning/exercises/04-grep/shakespeare.txt b/23-input-scanning/exercises/04-grep/shakespeare.txt
index cd46cce..bff5be6 100644
--- a/23-input-scanning/exercises/04-grep/shakespeare.txt
+++ b/23-input-scanning/exercises/04-grep/shakespeare.txt
@@ -7,6 +7,6 @@ take him and cut him out in little stars
 and he will make the face of heaven so fine
 that all the world will be in love with night
 and pay no worship to the garish sun
-oh i have bought the mansion of love
-but not possessed it and though i am sold
-not yet enjoyed
\ No newline at end of file
+oh I have bought the mansion of love
+but not possessed it and though I am sold
+not yet enjoyed
diff --git a/23-input-scanning/exercises/04-grep/solution/shakespeare.txt b/23-input-scanning/exercises/04-grep/solution/shakespeare.txt
index cd46cce..bff5be6 100644
--- a/23-input-scanning/exercises/04-grep/solution/shakespeare.txt
+++ b/23-input-scanning/exercises/04-grep/solution/shakespeare.txt
@@ -7,6 +7,6 @@ take him and cut him out in little stars
 and he will make the face of heaven so fine
 that all the world will be in love with night
 and pay no worship to the garish sun
-oh i have bought the mansion of love
-but not possessed it and though i am sold
-not yet enjoyed
\ No newline at end of file
+oh I have bought the mansion of love
+but not possessed it and though I am sold
+not yet enjoyed
diff --git a/24-structs/exercises/03-query-by-id/main.go b/24-structs/exercises/03-query-by-id/main.go
index a5b9710..87adaf8 100644
--- a/24-structs/exercises/03-query-by-id/main.go
+++ b/24-structs/exercises/03-query-by-id/main.go
@@ -29,7 +29,7 @@ package main
 //     wrong id
 //
 //     id 10
-//     sorry. i don't have the game
+//     sorry. I don't have the game
 //
 //     id 1
 //     #1: "god of war" (action adventure) $50
diff --git a/24-structs/exercises/03-query-by-id/solution/main.go b/24-structs/exercises/03-query-by-id/solution/main.go
index 0a8bd36..298e729 100644
--- a/24-structs/exercises/03-query-by-id/solution/main.go
+++ b/24-structs/exercises/03-query-by-id/solution/main.go
@@ -90,7 +90,7 @@ func main() {
 
 			g, ok := byID[id]
 			if !ok {
-				fmt.Println("sorry. i don't have the game")
+				fmt.Println("sorry. I don't have the game")
 				continue
 			}
 
diff --git a/24-structs/exercises/04-encode/solution/main.go b/24-structs/exercises/04-encode/solution/main.go
index e00b83a..99c08b2 100644
--- a/24-structs/exercises/04-encode/solution/main.go
+++ b/24-structs/exercises/04-encode/solution/main.go
@@ -92,7 +92,7 @@ func main() {
 
 			g, ok := byID[id]
 			if !ok {
-				fmt.Println("sorry. i don't have the game")
+				fmt.Println("sorry. I don't have the game")
 				continue
 			}
 
diff --git a/24-structs/exercises/05-decode/solution/main.go b/24-structs/exercises/05-decode/solution/main.go
index 33e9363..4e58539 100644
--- a/24-structs/exercises/05-decode/solution/main.go
+++ b/24-structs/exercises/05-decode/solution/main.go
@@ -130,7 +130,7 @@ func main() {
 
 			g, ok := byID[id]
 			if !ok {
-				fmt.Println("sorry. i don't have the game")
+				fmt.Println("sorry. I don't have the game")
 				continue
 			}
 
diff --git a/25-functions/exercises/refactor-to-funcs-1/main.go b/25-functions/exercises/refactor-to-funcs-1/main.go
index 7f3af05..0526931 100644
--- a/25-functions/exercises/refactor-to-funcs-1/main.go
+++ b/25-functions/exercises/refactor-to-funcs-1/main.go
@@ -139,7 +139,7 @@ func main() {
 
 			g, ok := byID[id]
 			if !ok {
-				fmt.Println("sorry. i don't have the game")
+				fmt.Println("sorry. I don't have the game")
 				continue
 			}
 
diff --git a/25-functions/exercises/refactor-to-funcs-1/solution/main.go b/25-functions/exercises/refactor-to-funcs-1/solution/main.go
index f44c102..390d9f0 100644
--- a/25-functions/exercises/refactor-to-funcs-1/solution/main.go
+++ b/25-functions/exercises/refactor-to-funcs-1/solution/main.go
@@ -66,7 +66,7 @@ func main() {
 
 			g, ok := byID[id]
 			if !ok {
-				fmt.Println("sorry. i don't have the game")
+				fmt.Println("sorry. I don't have the game")
 				continue
 			}
 
diff --git a/25-functions/exercises/refactor-to-funcs-2/main.go b/25-functions/exercises/refactor-to-funcs-2/main.go
index d79929d..4961873 100644
--- a/25-functions/exercises/refactor-to-funcs-2/main.go
+++ b/25-functions/exercises/refactor-to-funcs-2/main.go
@@ -119,7 +119,7 @@ func main() {
 
 			g, ok := byID[id]
 			if !ok {
-				fmt.Println("sorry. i don't have the game")
+				fmt.Println("sorry. I don't have the game")
 				continue
 			}
 
diff --git a/25-functions/exercises/refactor-to-funcs-2/solution/commands.go b/25-functions/exercises/refactor-to-funcs-2/solution/commands.go
index ce02198..db53a11 100644
--- a/25-functions/exercises/refactor-to-funcs-2/solution/commands.go
+++ b/25-functions/exercises/refactor-to-funcs-2/solution/commands.go
@@ -61,7 +61,7 @@ func cmdByID(cmd []string, games []game, byID map[int]game) bool {
 
 	g, ok := byID[id]
 	if !ok {
-		fmt.Println("sorry. i don't have the game")
+		fmt.Println("sorry. I don't have the game")
 		return true
 	}
 
diff --git a/25-functions/exercises/refactor-to-funcs-3/commands.go b/25-functions/exercises/refactor-to-funcs-3/commands.go
index ce02198..db53a11 100644
--- a/25-functions/exercises/refactor-to-funcs-3/commands.go
+++ b/25-functions/exercises/refactor-to-funcs-3/commands.go
@@ -61,7 +61,7 @@ func cmdByID(cmd []string, games []game, byID map[int]game) bool {
 
 	g, ok := byID[id]
 	if !ok {
-		fmt.Println("sorry. i don't have the game")
+		fmt.Println("sorry. I don't have the game")
 		return true
 	}
 
diff --git a/25-functions/exercises/refactor-to-funcs-3/solution/commands.go b/25-functions/exercises/refactor-to-funcs-3/solution/commands.go
index 5bffb60..92d06d1 100644
--- a/25-functions/exercises/refactor-to-funcs-3/solution/commands.go
+++ b/25-functions/exercises/refactor-to-funcs-3/solution/commands.go
@@ -65,7 +65,7 @@ func cmdByID(cmd []string, games []game, byID map[int]game) bool {
 
 	g, ok := byID[id]
 	if !ok {
-		fmt.Println("sorry. i don't have the game")
+		fmt.Println("sorry. I don't have the game")
 		return true
 	}
 
diff --git a/advfuncs/08-png-detector-with-panic/pngs/shakespeare-text.png b/advfuncs/08-png-detector-with-panic/pngs/shakespeare-text.png
index cd46cce..bff5be6 100644
--- a/advfuncs/08-png-detector-with-panic/pngs/shakespeare-text.png
+++ b/advfuncs/08-png-detector-with-panic/pngs/shakespeare-text.png
@@ -7,6 +7,6 @@ take him and cut him out in little stars
 and he will make the face of heaven so fine
 that all the world will be in love with night
 and pay no worship to the garish sun
-oh i have bought the mansion of love
-but not possessed it and though i am sold
-not yet enjoyed
\ No newline at end of file
+oh I have bought the mansion of love
+but not possessed it and though I am sold
+not yet enjoyed
diff --git a/advfuncs/08-png-detector/pngs/shakespeare-text.png b/advfuncs/08-png-detector/pngs/shakespeare-text.png
index cd46cce..bff5be6 100644
--- a/advfuncs/08-png-detector/pngs/shakespeare-text.png
+++ b/advfuncs/08-png-detector/pngs/shakespeare-text.png
@@ -7,6 +7,6 @@ take him and cut him out in little stars
 and he will make the face of heaven so fine
 that all the world will be in love with night
 and pay no worship to the garish sun
-oh i have bought the mansion of love
-but not possessed it and though i am sold
-not yet enjoyed
\ No newline at end of file
+oh I have bought the mansion of love
+but not possessed it and though I am sold
+not yet enjoyed
diff --git a/advfuncs/10-image-detector-recover/pngs/shakespeare-text.png b/advfuncs/10-image-detector-recover/pngs/shakespeare-text.png
index cd46cce..bff5be6 100644
--- a/advfuncs/10-image-detector-recover/pngs/shakespeare-text.png
+++ b/advfuncs/10-image-detector-recover/pngs/shakespeare-text.png
@@ -7,6 +7,6 @@ take him and cut him out in little stars
 and he will make the face of heaven so fine
 that all the world will be in love with night
 and pay no worship to the garish sun
-oh i have bought the mansion of love
-but not possessed it and though i am sold
-not yet enjoyed
\ No newline at end of file
+oh I have bought the mansion of love
+but not possessed it and though I am sold
+not yet enjoyed
diff --git a/advfuncs/10b-named-params/pngs/shakespeare-text.png b/advfuncs/10b-named-params/pngs/shakespeare-text.png
index cd46cce..bff5be6 100644
--- a/advfuncs/10b-named-params/pngs/shakespeare-text.png
+++ b/advfuncs/10b-named-params/pngs/shakespeare-text.png
@@ -7,6 +7,6 @@ take him and cut him out in little stars
 and he will make the face of heaven so fine
 that all the world will be in love with night
 and pay no worship to the garish sun
-oh i have bought the mansion of love
-but not possessed it and though i am sold
-not yet enjoyed
\ No newline at end of file
+oh I have bought the mansion of love
+but not possessed it and though I am sold
+not yet enjoyed