1. What is the fundamental concept about the metric system that makes it possible to measure the mass of an unknown object with water?

First you take the board and put a pencil in about the middle and try to get it to balance (make sure the side where the item will be will be down when you put the item on there) tape the bottom of of a bottle (cut of the bottom of a bottle, then tape it), put a bottle in the bottom part of the cut bottle bottom on the second bottle cut from where it star to become as big as possible and up off. Put the object on the other side make sure it's not too heavy. Then you can start pouring water into the bottle. 

2. Any balance or scale has a maximum amount of mass it can measure. What is the maximum mass that your homemade water balance can measure?  Explain.

The maximum that can be put in the bottle it about 1 liter because the bottle is 1 liter but, then you cut a bit off of the bottle (bottle should be empty when you cut it, should be an old bottle).