Controls/Variables, Scientific Notation & Metric Conversions Daily Objective: (Applying) Warm-up: Recall from yesterday that there are two variables in each experiment; the dependent & independent variable. Look at these 2 terms and discuss, in your own words, what you think they mean. Look at your TOD from yesterday and hypothesize what is the independent variable and what is the dependent variable in your experiment Identify the independent variable and dependent variables in various experiments.

Independent Variable The independent variable is the one that is changed by the scientist. To insure a fair test, a good experiment has only one independent variable. As the scientist changes the independent variable, he or she observes what happens. 2

Therefore, it DEPENDS on the Independent Variable! The scientist focuses his or her observations on the dependent variable to see how it responds to the change made to the independent variable. Therefore, it DEPENDS on the Independent Variable!

For Example For example, if you open a faucet (the independent variable), the quantity of water flowing (dependent variable) changes in response--you observe that the water flow increases. The number of dependent variables in an experiment varies, but there is often more than one.

Controls/Constants Controlled variables are quantities that a scientist wants to remain constant, and he must observe them as carefully as the dependent variables.

For Example A control/constant in the water faucet experiment could be the size of the faucet. You would want to make sure to “control” and keep the size constant because changing the size of the faucet will make it difficult to determine if it is the size of the faucet or the degree that the faucet is turned on that effects the quantity of water.

Scientific Notation

How wide is our universe? 210,000,000,000,000,000,000,000 miles (22 zeros) This number is written in decimal notation. When numbers get this large, it is easier to write them in scientific notation.

A number is expressed in scientific notation when it is in the form a x 10n where a is between 1 and 10 and n is an integer 9

Write the width of the universe in scientific notation. 210,000,000,000,000,000,000,000 miles Where is the decimal point now? After the last zero. Where would you put the decimal to make this number be between 1 and 10? Between the 2 and the 1

2.10,000,000,000,000,000,000,000. How many decimal places did you move the decimal? 23 When the original number is more than 1, the exponent is positive. The answer in scientific notation is 2.1 x 1023

1) Express 0.0000000902 in scientific notation. Where would the decimal go to make the number be between 1 and 10? 9.02 The decimal was moved how many places? 8 When the original number is less than 1, the exponent is negative. 9.02 x 10-8

Convert the Following 1) 3,400 2) 0.000023 3) 101,000 4) 0.010 5) 2.30 x 104 6) 1.76 x 10-3 7) 1.901 x 10-7 8) 8.65 x 106