This is a fun sort of thing to do! It seems like a weird way to compare the relative weights of some other liquids to that of water. (That does NOT mean you are to go around asking your aunts and uncles how much they weigh! The word "relative" in this sense means "as compared to.") We will see what liquids are heavier than water and what liquids are not as heavy as water.

We can use any large, glass container such as an aquarium (without fish). The aquarium will substitute for a scale. We'll add water to the aquarium until it is about one-fourth full.

We have some small, labeled, pill bottles with tight lids, into which have been put some different liquids: water, milk, cooking oil, motor oil, syrup, honey, tomato juice, liquid dishwashing detergent, and egg yolk. Any liquids that people use in their daily lives and are easy to get can be used for this experiment. We don't need to bother with dinosaur milk!

Do notice that the little bottles have to be completely full, and the caps have to be really tight, so that the bottles don't have air in them, and so that water from our aquarium won't leak into the bottles. Best to put tape around the caps, just to be sure.

First, we put the bottle of water into the aquarium. See how it floats in the aquarium, just below the surface of the aquarium water? (The bottle weighs a little bit, and holds it down.)

Now, let's put the other bottles into the aquarium, and see where they float--whether they are heavier or lighter than the bottle of water.

We need to make a list of the liquids in the order of their weights, with the lightest one at the top of the list.

Next, we can take out the bottles, wipe them dry, and weigh them on our postage scale to see if their weights were shown accurately in our experiment.

How can it be that the same amount of different liquids do not weigh the same?