diff --git a/book/src/SUMMARY.md b/book/src/SUMMARY.md
index e61db97..a121b9f 100644
--- a/book/src/SUMMARY.md
+++ b/book/src/SUMMARY.md
@@ -15,3 +15,8 @@
   * [The VCount Register](ch02/the_vcount_register.md)
   * [light_cycle](ch02/light_cycle.md)
 * [Ch 3: Memory and Objects](ch03/index.md)
+  * [Tiled Backgrounds](ch03/tiled_backgrounds.md)
+  * [Object Basics](ch03/object_basics.md)
+  * [GBA Memory](ch03/gba_memory.md)
+  * [GBA RNG](ch03/gba_rng.md)
+  * [memory_game](ch03/memory_game.md)
diff --git a/book/src/ch03/index.md b/book/src/ch03/index.md
index 509119f..1199abd 100644
--- a/book/src/ch03/index.md
+++ b/book/src/ch03/index.md
@@ -1,17 +1,33 @@
 # Ch 3: Memory and Objects
 
 Alright so we can do some basic "movement", but we left a big trail in the video
-memory of where we went. Most of the time that's not what we want at all. If we
-want to draw something over top of our background without trashing the
-background memory that's an "object" (but not in the "Object Oriented" sense).
-You might recall that objects have their own layer that you can enable in the
-display control register.
+memory of everywhere we went. Most of the time that's not what we want at all.
+If we want more hardware support we're going to have to use a new video mode. So
+far we've only used Mode 3, but modes 4 and 5 are basically the same. Instead,
+we'll focus on using a tiled mode. The tiled modes take less time to arrange,
+which means more time for game computations. If your game has much complexity at
+all, you'll naturally want to use a tiled mode to display it.
 
-Of course, once we're drawing these objects we'll want some scratch space to
-work with them a bit, so we'll finally go over the GBA's full memory layout.
+Tiled modes bring us two big new concepts that each have their own complexity:
+backgrounds and objects. They share some concepts, but fundamentally the
+background is for creating a very large static space that you can scroll around
+the view within, and the objects are about having a few moving bits that appear
+over the background. Careful use of backgrounds and objects is key to having the
+best looking GBA game, so we won't even be able to cover it all in a single
+chapter.
 
-And since most games are pretty boring without an RNG, we'll cover the kinds of
-RNG that you might want to include in a GBA game.
+Of course, once we're all set drawing the objects and backgrounds, we'll want
+them to start keeping track of what's where, and maybe store info on stuff
+that's off screen. That means it's finally time to go over the GBA's memory
+layout so that we know where we have scratch space to work with.
 
-Then we'll do something or other that includes moving things and and RNG...
-which is pretty much any game at all.
+And, of course, since most games are pretty boring if they're totally static
+we'll touch on the kinds of RNG implementations you might want to have on a GBA.
+Most general purpose RNGs that you find are rather big compared to the amount of
+memory we want to give them, and they often use a lot of `u64` operations, so
+they end up much slower on a 32-bit machine like the GBA (you can lower 64-bit
+ops to combinations of 32-bit ops, but that's quite a bit more work). We'll
+cover a few RNG options that size down the RNG to a good size and a good speed
+without trading away too much in terms of quality.
+
+To top it all off, we'll make a simple memory game sort of thing.