I know that fresh water will freeze faster than salt water but I need to fill in a table. The table shows some variables which are the amount of water and the amount of salet. I need to write how I would control each variable and I do not quite understand what to do?

http://www.fao.org/DOCREP/003/P3407E/P3407E04.HTM

http://nsidc.org/seaice/intro.html

To control the variables of water and salt in your experiment, you need to determine the specific amounts of each that you want to test. Here's how you can control each variable:

1. Controlling the amount of water:
- Start by deciding on a specific volume or quantity of water you want to test. This could be measured in liters, milliliters, or any other unit of volume.
- Use a measuring tool, such as a graduated cylinder or measuring cup, to accurately measure and control the amount of water you add to each sample.
- Ensure that the water temperature is consistent across all the samples before starting the experiment. This can be achieved by using the same water source or allowing sufficient time for the samples to equilibrate to the same temperature.

2. Controlling the amount of salt:
- Determine the concentration of salt you want to include in your saltwater samples. This can be measured in grams of salt per liter of water (g/L) or any other appropriate unit.
- Use a weighing scale or balance to measure the exact amount of salt you need based on your desired concentration.
- Dissolve the salt completely in the water by stirring or shaking the mixture until no particles remain.
- Ensure that the salt is evenly distributed throughout the sample by ensuring sufficient mixing.

By carefully controlling these variables, you can ensure that the only difference between the samples is the ratio of water to salt, allowing you to observe and compare the freezing rates.