I cannot remember where I found this but it is a fun little treat to make with the kids.
1 packet of orange jello
Make up orange jello according to the packet instructions. Set aside for 20 minutes to cool.
Slice oranges in half and scoop out the flesh, using a small knife or spoon. Fill the orange cavities with cooled jello. Place the orange halves, upright, on a tray. Refrigerate for 3 hours or until set.