Reuse those Avocado seeds bought at the store!
This is a great science project for the kiddos.
After you purchase a yummy avocado, learn how to grow one with this image.
It takes several weeks, even months for the avocado to crack! So, be patient.
Keep a daily or weekly log of the changes the seed is going through. If the child cannot write, they can draw. Have them write/draw what they see or what they feel. Let them imagine how the tree would look like. Let them estimate how long they think it would take for the seed to crack.
The seed will turn into a tree in several years, so this project would be perfect for a place where you can visit in the long haul or at least drive through, or in your family home.