Astudent is designing a controlled experiment to test whether the amount of water that a plant receives affects its growth. which variables should the student hold constant and which variable should the student manipulate?

1. Constant variable-amount of soil and number of pots

2. Independent variable-the time period and the amount of water

Explanation:

A scientific experimental design must include three types of variable:  

1. Independent variable- the variable which can be manipulated or can be changed manually or on their own

2. Dependent variable- the variable which has to be tested  

3. Constant variable- which is kept constant throughout the experiment

In the given question, the student wants to study the effect of the amount of water on the growth of the plants. So, the designed experiment must contain:

1. Dependent variable- the growth of the plant

2. Independent variable- the time period and the amount of water

3. Constant variable - the amount of soil and number of pots