diff --git a/2_21.sch b/2_21.sch
new file mode 100644
index 0000000..d59da13
--- /dev/null
+++ b/2_21.sch
@@ -0,0 +1,10 @@
+(define (square x) (* x x))
+
+(define (square-list-1 items)
+  (if (null? items)
+      '()
+      (cons (square (car items)) (square-list-1 (cdr items)))))
+
+(define (square-list-2 items)
+  (map square items))
+
diff --git a/2_22.txt b/2_22.txt
new file mode 100644
index 0000000..4f1f977
--- /dev/null
+++ b/2_22.txt
@@ -0,0 +1,8 @@
+The list is in the reverse order because each call to cons puts the next
+item in front of the previous one.  We are iterating through the input
+list from left to right but are adding to the result from right to left.
+
+The second solution doesn't work because cons takes a single value as
+its first value and a list as its second.
+
+
diff --git a/2_23.sch b/2_23.sch
new file mode 100644
index 0000000..2736bb6
--- /dev/null
+++ b/2_23.sch
@@ -0,0 +1,4 @@
+(define (for-each f l)
+  (if (not (null? l))
+      (begin (f (car l))
+      	     (for-each f (cdr l)))))