To set up activity terms, as a Platform Manager:
  1. Navigate to Core
  2. Settings > School Information
  3. Select Years & Terms
  4. Select the correct school year
  5. Scroll down to the Activity Terms and Click +Add 
  6. Complete the form, then click Save & Close
Here you will need to add the terms your school will have for activities next year. You can look at the past activity terms for reference if it will be the same this year.