A dairy farmer wanted to increase the amount of milk produced by his cows. He decides to test the effect of a particular feed additive. He gives half of his herd the additive. He maintains the amount of grazing time, the amount of water the cows drink per day, and even how often the cow gets chased by the local dog the same for all the cows. Each day the farmer milks the cows at the same time and compares the volume of milk.

This question is incomplete; based on the understanding of the question, it aims at identifying the variables in the experiment conducted by the dairy farmer. The following variables will be provided in the Independent, dependent, Control variable, Control group, Experimental group. The answers are:

Independent variable: FEED ADDITIVE

Dependent variable: AMOUNT (VOLUME) OF MILK PRODUCED

Constants: same amount of grazing time, the same amount of water the cows drink per day and the same frequency of how dogs chases the cows.

Control group: Herds that were not given the additive.

Experimental group: Herds that were given the additive

Explanation:

The independent variable in an experiment refers to the variable which is manipulated or changed in order to bring about a responding effect. The FEED ADDITIVE is the independent variable in this experiment.

The dependent variable is the variable that responds to the changes made to the independent variable. In this case, it is the AMOUNT/VOLUME OF MILK produced by the cows that responds to the effect of the feed additive, hence, it is the dependent variable.

In an experiment, a controlled variable or CONSTANT is the variable that is kept constant or unchanged throughout the experiment. In this case, the constants are the same amount of grazing time, the same amount of water the cows drink per day and the same frequency of how dogs chases the cows.

A CONTROL GROUP is the group that does not receive any experimental treatment in the experiment. It is used to compare the effect of the independent variable on the dependent variable. In this experiment, the control group are the HERDS that did not receive the feed additives.

The experimental group, on the contrary, are the groups that were subjected to experimental treatment. In this case, the experimental group are the HERDS that were given the feed additives.

It's challenging because it demonstrates the principle of relative height. Objects in our upper field of vision appear farther away than objects in our lower field of vision. Vertical objects appear taller than objects near the ground, which are closer to us. The Ebbinghaus illusion demonstrates the difficulty we have perceiving objects in contrast with their surroundings. There is also the Poggendorf illusion that makes two lines appear to be joined when they are not. There are many more illusion tests that makes something seem like it's to our profound knowledge.