What is the independent, dependant, and controlled variable for the following experiments.
experiment 1
part 1:
two people are shown talking about how much they like iced tea. person 1 argues that iced tea is better at room temperature (i. e., 20℃). person 2 argues that iced tea is better at 0℃. to settle their argument, they decide to reduce the temperature of a pitcher of iced tea from 20℃ to 0℃ and compare the taste at both temperatures.
the video pauses here to allow students to hypothesize what will happen as the temperature of the iced tea is reduced from 20℃ to 0℃.
part 2:
the people place a thermometer inside a pitcher of iced tea and then place the pitcher inside a freezer. when the pitcher first goes into the freezer, the thermometer reads −20℃.
gradually, show the thermometer’s red line (or the number, if it’s a digital thermometer) dropping from 20℃ to 0℃.
when the thermometer reads 0℃, the people should remove the pitcher from the freezer. one person should attempt to remove the thermometer, only to find that the iced tea has frozen and the thermometer is stuck.
experiment 2
part 1:
a chef is shown stirring salt and other seasonings into a pot of soup that is resting on a stove burner. the chef tastes the soup and proclaims it good. the chef then turns up the stove burner and leaves.
the video pauses here to allow students to hypothesize what will happen to the soup as it heats up on the burner.
part 2
the soup in the pot gradually begins to boil; we can see steam rising from the soup.
after the soup has boiled for a while, the chef returns to the pot and tastes the soup. she or he makes a face and proclaims the soup too salty. she or he wonders what has happened.
the video pauses here to allow students to hypothesize why the soup has become too salty as it boiled, and also to predict how the chef could make the soup taste good again.
part 3:
the chef measures the soup’s volume and discovers that there is 4.5 liters of soup in the pot. rereading the recipe, the chef finds that to make the soup, she or he used five liters of water. therefore, she or he concludes that as the soup boiled on the stove, 500 ml of water evaporated into steam.
the chef concludes that if s/he adds 500 ml of water to the soup, she or he will restore the original balance of water to seasoning, and the flavor will improve.