Challenge Not yet complete... here's what's wrong:
The 'Day_of_the_Week__c' is not reporting the correct day of the week (Monday, Tuesday, etc.)
I created the field on the Contact object  per the requirements and created the formula to return a text field with the day of the for "today". I tested my formula and it works but it does not pass the check challenge. The formula I am using is:

CASE(MOD(Today()- DATE(1900,1,7), 7), 0, 'Sunday', 1, 'Monday',2,'Tuesday',3,'Wednesday',4,'Thursday',5,'Friday',6,'Friday','error')