diff --git a/08_simplejumping/main.c b/08_simplejumping/main.c
index 8a3fe1a..ec6e6be 100644
--- a/08_simplejumping/main.c
+++ b/08_simplejumping/main.c
@@ -1,7 +1,7 @@
 #include <gb/gb.h>
 #include <stdio.h>
 
-INT16 playerlocation[2]; // stores two INT16 x and y position of player
+UINT16 playerlocation[2]; // stores two UINT16 x and y position of player
 BYTE jumping;
 INT8 gravity = -2;
 INT16 currentspeedY;
diff --git a/09_metasprites/GameCharacter.c b/09_metasprites/GameCharacter.c
index b895813..17f8024 100644
--- a/09_metasprites/GameCharacter.c
+++ b/09_metasprites/GameCharacter.c
@@ -1,10 +1,8 @@
 #include <gb/gb.h>
 
 //generical character structure: id, position, graphics
-struct GameCharacter {
+typedef struct {
 	UBYTE spritids[4]; // all characters use 4 sprites
 	UINT8 x;
 	UINT8 y;
-	UINT8 width;
-	UINT8 height;
-};
\ No newline at end of file
+} GameCharacter;
diff --git a/09_metasprites/main.c b/09_metasprites/main.c
index 880dcfa..5bfc791 100644
--- a/09_metasprites/main.c
+++ b/09_metasprites/main.c
@@ -3,66 +3,47 @@
 #include "GameCharacter.c"
 #include "GameSprites.c"
 
-struct GameCharacter ship;
-struct GameCharacter bug;
-UBYTE spritesize = 8;
+#define SPRITE_SIZE 8
+
+GameCharacter ship;
+GameCharacter bug;
 
 void performantdelay(UINT8 numloops){
-    UINT8 i;
-    for(i = 0; i < numloops; i++){
+    for(UINT8 i = 0; i < numloops; i++){
         wait_vbl_done();
     }     
 }
 
-void movegamecharacter(struct GameCharacter* character, UINT8 x, UINT8 y){
+void movegamecharacter(GameCharacter* character, UINT8 x, UINT8 y){
+    // implies that four tiles from the value of tile_start and up are for the same meta sprite
+    // and are arranged clockwise, starting from the top left 8x8 quadrant
     move_sprite(character->spritids[0], x, y);
-    move_sprite(character->spritids[1], x + spritesize, y);
-    move_sprite(character->spritids[2], x, y + spritesize);
-    move_sprite(character->spritids[3], x + spritesize, y + spritesize);
+    move_sprite(character->spritids[1], x + SPRITE_SIZE, y);
+    move_sprite(character->spritids[2], x, y + SPRITE_SIZE);
+    move_sprite(character->spritids[3], x + SPRITE_SIZE, y + SPRITE_SIZE);
 }
 
-void setupship(){
-    ship.x = 80;
-    ship.y = 130;
-    ship.width = 16;
-    ship.height = 16;
-
-    // load sprites for ship
-    set_sprite_tile(0, 0);
-    ship.spritids[0] = 0;
-    set_sprite_tile(1, 1);
-    ship.spritids[1] = 1;
-    set_sprite_tile(2, 2);
-    ship.spritids[2] = 2;
-    set_sprite_tile(3, 3);
-    ship.spritids[3] = 3;
-
-    movegamecharacter(&ship, ship.x, ship.y);
-}
+void setup_GameCharacter(GameCharacter* character, UINT8 x_position, UINT8 y_position, UINT8 tile_start){
+    character->x = x_position;
+    character->y = y_position;
+
+    // load sprites for sprite
+    // starts reading from tile_start and increments up by one to retrieve sprite ids
+    for(UINT8 i=0; i<4; i++) {
+		set_sprite_tile(tile_start, tile_start);
+        character->spritids[i] = tile_start;
 
-void setupbug(){
-    bug.x = 30;
-    bug.y = 0;
-    bug.width = 16;
-    bug.height = 16;    
-
-    // load sprites for bug
-    set_sprite_tile(4, 4);
-    bug.spritids[0] = 4;
-    set_sprite_tile(5, 5);
-    bug.spritids[1] = 5;
-    set_sprite_tile(6, 6);
-    bug.spritids[2] = 6;
-    set_sprite_tile(7, 7);
-    bug.spritids[3] = 7;
-
-    movegamecharacter(&bug, bug.x, bug.y);
+        tile_start++;
+	}
+
+    movegamecharacter(character, character->x, character->y);
 }
 
 void main(){
     set_sprite_data(0, 8, GameSprites);
-    setupship();
-    setupbug();
+
+    setup_GameCharacter(&ship, 80, 130, 0);
+    setup_GameCharacter(&bug, 30, 0, 4);
 
     SHOW_SPRITES;
     DISPLAY_ON;
diff --git a/10_sprite_collision/main.c b/10_sprite_collision/main.c
index 7d33630..f2adfe7 100644
--- a/10_sprite_collision/main.c
+++ b/10_sprite_collision/main.c
@@ -3,70 +3,62 @@
 #include "GameCharacter.c"
 #include "GameSprites.c"
 
+#define SPRITE_SIZE 8
+#define GAMECHARACTER_SIZE 16
+
 GameCharacter ship;
 GameCharacter bug;
-UBYTE spritesize = 8;
 
 void performantdelay(UINT8 numloops){
-    UINT8 i;
-    for(i = 0; i < numloops; i++){
+    for(UINT8 i = 0; i < numloops; i++){
         wait_vbl_done();
     }     
 }
 
-UBYTE checkcollisions(GameCharacter* one, GameCharacter* two){
-    return (one->x >= two->x && one->x <= two->x + two->width) && (one->y >= two->y && one->y <= two->y + two->height) || (two->x >= one->x && two->x <= one->x + one->width) && (two->y >= one->y && two->y <= one->y + one->height);
-}
+// takes two GameCharacter's and return's true if the sprites overlap
+UBYTE checkcollisions(GameCharacter* one, GameCharacter* two){ 
+    // the width and height of a box is always the same and for this box its always 16
+
+    return     (one->x >= two->x && one->x <= two->x + GAMECHARACTER_SIZE)  
+            && (one->y >= two->y && one->y <= two->y + GAMECHARACTER_SIZE)
+            // check if the first sprite x and y position is either on or inside the borders of the second sprite
+            ||
+            
+               (two->x >= one->x && two->x <= one->x + GAMECHARACTER_SIZE) 
+            && (two->y >= one->y && two->y <= one->y + GAMECHARACTER_SIZE);
+            // or check if the second sprite is inside the second            
+} 
 
 void movegamecharacter(GameCharacter* character, UINT8 x, UINT8 y){
+    // implies that four tiles from the value of tile_start and up are for the same meta sprite
+    // and are arranged clockwise, starting from the top left 8x8 quadrant
     move_sprite(character->spritids[0], x, y);
-    move_sprite(character->spritids[1], x + spritesize, y);
-    move_sprite(character->spritids[2], x, y + spritesize);
-    move_sprite(character->spritids[3], x + spritesize, y + spritesize);
+    move_sprite(character->spritids[1], x + SPRITE_SIZE, y);
+    move_sprite(character->spritids[2], x, y + SPRITE_SIZE);
+    move_sprite(character->spritids[3], x + SPRITE_SIZE, y + SPRITE_SIZE);
 }
 
-void setupship(){
-    ship.x = 80;
-    ship.y = 130;
-    ship.width = 16;
-    ship.height = 16;
-
-    // load sprites for ship
-    set_sprite_tile(0, 0);
-    ship.spritids[0] = 0;
-    set_sprite_tile(1, 1);
-    ship.spritids[1] = 1;
-    set_sprite_tile(2, 2);
-    ship.spritids[2] = 2;
-    set_sprite_tile(3, 3);
-    ship.spritids[3] = 3;
-
-    movegamecharacter(&ship, ship.x, ship.y);
-}
+void setup_GameCharacter(GameCharacter* character, UINT8 x_position, UINT8 y_position, UINT8 tile_start){
+    character->x = x_position;
+    character->y = y_position;
 
-void setupbug(){
-    bug.x = 30;
-    bug.y = 0;
-    bug.width = 16;
-    bug.height = 16;    
-
-    // load sprites for bug
-    set_sprite_tile(4, 4);
-    bug.spritids[0] = 4;
-    set_sprite_tile(5, 5);
-    bug.spritids[1] = 5;
-    set_sprite_tile(6, 6);
-    bug.spritids[2] = 6;
-    set_sprite_tile(7, 7);
-    bug.spritids[3] = 7;
-
-    movegamecharacter(&bug, bug.x, bug.y);
+    // load sprites for sprite
+    // starts reading from tile_start and increments up by one to retrieve sprite ids
+    for(UINT8 i=0; i<4; i++) {
+		set_sprite_tile(tile_start, tile_start);
+        character->spritids[i] = tile_start;
+
+        tile_start++;
+	}
+
+    movegamecharacter(character, character->x, character->y);
 }
 
 void main(){
     set_sprite_data(0, 8, GameSprites);
-    setupship();
-    setupbug();
+
+    setup_GameCharacter(&ship, 80, 130, 0);
+    setup_GameCharacter(&bug, 30, 0, 4);
 
     SHOW_SPRITES;
     DISPLAY_ON;