measuring without measuring

[logenp17]

How can you without any measuring device and using a 16 ounce cup measure a volume of water that is exactly 8 ounces . you can't eye ball it

[Rev. Green]

Not sure if this constitutes "eye balling", but you could half fill the 16 ounce cup by successive approximation. Put some water in the cup, mark the level, put a transparent lid on the cup, invert it, compare the water level with the mark, return the cup the correct way up, remove the lid, adjust the water level, repeat.