# Daily Challenge, 9/29 Scientists often make generalizations – broad statements or rules that usually apply in most situations. Think about the gum experiments.

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Daily Challenge, 9/29 Scientists often make generalizations – broad statements or rules that usually apply in most situations. Think about the gum experiments we did last week and the results we are sharing in class. Write at least two generalizations about how the mass, volume, and/or density of gum changes when you chew it. “In general, the…”

Variables in a Scientific Experiment Independent Variable – the “cause” or thing you manipulated/changed to see what would happen Dependent Variable – the “effect” or thing that responded to the independent variable Controlled Variables – variables that are held constant to make a fair test so you can be sure the independent variable was the only cause The experimental control group is the unchanged independent variable you use for comparison – don’t confuse it with controlled variables.

Example Experiment Some students do an experiment to figure out what kind of acid dissolves limestone the fastest. They get 8 pieces of limestone that are the same size and shape and measure the mass of each one. Two pieces are put into a plastic container with 100 mL of plain water. Two pieces are put into a plastic container with 100 mL of hydrochloric acid. Two pieces are put into a plastic container with 100 mL of nitric acid. Two pieces are put into a plastic container with 100 mL of acetic acid. All the plastic containers are kept in the same place. Every 6 hours, each piece of limestone is weighed to determine its mass. Identify the Independent Variable. A.type of rock B.size of container C.amount of liquid D.type of liquid E.weight of rock dissolved F.container location

Example Experiment Some students do an experiment to figure out what kind of acid dissolves limestone the fastest. They get 8 pieces of limestone that are the same size and shape and measure the mass of each one. Two pieces are put into a plastic container with 100 mL of plain water. Two pieces are put into a plastic container with 100 mL of hydrochloric acid. Two pieces are put into a plastic container with 100 mL of nitric acid. Two pieces are put into a plastic container with 100 mL of acetic acid. All the plastic containers are kept in the same place. Every 6 hours, each piece of limestone is weighed to determine its mass. Identify the Dependent Variable. A.type of rock B.size of container C.amount of liquid D.type of liquid E.weight of rock dissolved F.container location

Example Experiment Some students do an experiment to figure out what kind of acid dissolves limestone the fastest. They get 8 pieces of limestone that are the same size and shape and measure the mass of each one. Two pieces are put into a plastic container with 100 mL of plain water. Two pieces are put into a plastic container with 100 mL of hydrochloric acid. Two pieces are put into a plastic container with 100 mL of nitric acid. Two pieces are put into a plastic container with 100 mL of acetic acid. All the plastic containers are kept in the same place. Every 6 hours, each piece of limestone is weighed to determine its mass. Identify the Controlled Variables. A.type of rock B.size of container C.amount of liquid D.type of liquid E.rocks in water F.container location

Example Experiment Some students do an experiment to figure out what kind of acid dissolves limestone the fastest. They get 8 pieces of limestone that are the same size and shape and measure the mass of each one. Two pieces are put into a plastic container with 100 mL of plain water. Two pieces are put into a plastic container with 100 mL of hydrochloric acid. Two pieces are put into a plastic container with 100 mL of nitric acid. Two pieces are put into a plastic container with 100 mL of acetic acid. All the plastic containers are kept in the same place. Every 6 hours, each piece of limestone is weighed to determine its mass. Identify the Experimental Control Group. A.type of rock B.size of container C.amount of liquid D.type of liquid E.rocks in water F.container location

Daily Challenge, 10/1 A student does an experiment to see how the amount of watering affects how tall a bean plant grows. What is the independent variable? What is the dependent variable? What would be a good experimental control group for this experiment? Name 5 other variables that should be controlled or held constant.

Intro to Earth Science Quiz TOMORROW TOPICS to Review scientific method variables – independent, dependent, & controlled branches of Earth Science geology, meteorology, oceanography, astronomy metric system standard units & conversions density – how to calculate it scientific models types, purpose, limitations HOW to Review read through & organize worksheets, notes, handouts review notes, assignments, & challenges on Blackboard review chapter 1 in Holt text answer review questions

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