Correct apostrophe

exercises/grade-school/description.md

@@ -17,5 +17,5 @@ In the end, you should be able to:
     We have Anna, Barb, and Charlie in grade 1, Alex, Peter, and Zoe in grade 2, and Jim in grade 5.
     So the answer is: Anna, Barb, Charlie, Alex, Peter, Zoe, and Jim."
 
-Note that all our students only have one name (it’s a small town, what do you want?), and each student cannot be added more than once to a grade or the roster.
+Note that all our students only have one name (it's a small town, what do you want?), and each student cannot be added more than once to a grade or the roster.
 If a test attempts to add the same student more than once, your implementation should indicate that this is incorrect.