To complete the Indian Summer goal, you need to visit ten Neighbors, buy one Swimming Hole, and collect one Schoolhouse Daily Bonus. This is a very straightforward and you can probably finish this after you get it.
As for the Swimming Hole, you can purchase it from the Market. If you already own one, you can store it inside your Storage Shed and place it again in your homestead.
When you complete the Indian Summer Goal, you’ll receive 250 XP and 1,000 Coins. This will also unlock the fourth and last part of the Back to School Goals.
Did you find this goal sort of a letdown for being too easy? You might be delayed with this goal if you have collected the Schoolhouse Daily Bonus before getting the Indian Summer Goal. That means you have to wait for at least 24 hours before you can collect the daily bonus again.