add more information on variables

diff --git a/r/learning_r/variables_and_objects.mdwn b/r/learning_r/variables_and_objects.mdwn
index 202dd8b388898915f4beb084de5193172410e0ca..f75c164cd006940e2b95fd107f1c14d6fd732b76 100644 (file)
--- a/r/learning_r/variables_and_objects.mdwn
+++ b/r/learning_r/variables_and_objects.mdwn
@@ -4,10 +4,25 @@ Variables and Objects
 ---------------------
 
 Like most computer languages, R uses variables as a means of storing
-information in memory and retrieving it later. A variable 
+information in memory and retrieving it later. Variables can be
+assigned to using the `<-` or `=` operator. For example, to assign the
+number `5` to the variable `foo`, you would write
+
+[[!sweavealike echo=1 results="hide" code="""
+foo <- 5
+"""]]
+
+Variables can retrieved simply by referring to them by name. For
+example, to add `8` to the variable `foo` and store the result in
+`bar`, you would do the following:
+
+[[!sweavealike echo=1 results="hide" code="""
+bar <- foo + 8
+"""]]
+
 
 In R, variables are more correctly called objects, because they have
-structure and do not directly refer to a memory.
+structure and do not directly refer to a specific memory location.
 
 Basic Types
 ----------