Here is how to extend a class date -
Select the class on the calendar you wish to extend
Select 'Duplicate class'
3. Notice that all the class information is already filled in
4. Change the START DATE to the week after the END DATE of the original class. This way you are telling the system to continue this class after the end date.
5. Change the END DATE to the new END DATE you wish the class to end
6. Select the reoccurring type (Weekly or Monthly)