diff --git a/visualize.Rmd b/visualize.Rmd
index 30a680f..955efb0 100644
--- a/visualize.Rmd
+++ b/visualize.Rmd
@@ -91,7 +91,7 @@ The rest of this chapter will show you how to complete and extend this template
      
 1.  Make a scatterplot of `hwy` vs `cyl`.
 
-1.  What happens if you make a scatterplot of `class` vs `drv`. Why is
+1.  What happens if you make a scatterplot of `class` vs `drv`? Why is
     the plot not useful?
 
 ## Aesthetic mappings