Before you go into the Spirit Temple as a child, you might want to take care of unfinished business in the past. This page lists the things that you might want to do before traveling forward in time again.
Mask Trading as a Child
Read the mask trading sequence page to find out how to unlock all of the masks. You can only do this as child Link.
Collecting Gold Skulltulas as a Child
Check the Gold Skulltula guide to see a list of Gold Skulltulas that you can only collect as a child.
Planting Magic Beans as a Child
There is no soft soil when you are an adult, so you have to plant Magic Beans and drop bugs into the soft soil when you are a child. Some of the soft soil locations can only be accessed after you learn the temple warp songs as an adult. Read the list of soft soil locations to find out where to go to plant Magic Beans and drop bugs in to get Gold Skulltulas.
Collecting Pieces of Heart as a Child
Read the list of pieces of heart to check if there are any that you might have missed as a child.
Make sure that you have a Magic Bean and a bug in a bottle, then play the Requiem of Spirit to go to the Desert Colossus. Just outside of the temple entrance, there is soft soil. Drop a bug into it and kill the Gold Skulltula, then plant the Magic Bean.
Equip the Hylian Shield, then go into the Spirit Temple as a child.