Scientific Method

What is Science? Science is a method for studying the natural world. It is a process that uses observation and investigation to gain knowledge about events in nature.

Scientific Method An organized set of investigation procedures is called a scientific method. Six common steps found in scientific methods are shown.

Controlled Experiment Variables – factors in an experiment that can be changed. Independent Variable – The variable that you change in the experiment (the amount of fertilizer used). Dependent Variable – the variable that may change due to the independent variable (growth in the height of the plant).

Controlled Experiment (2) Control Group – A group that is not changed in an experiment (one plant that is not fertilized). Experimental Group – A group in an experiment that has had one variable changed (The plants that were given fertilizer). Constants – A factor that does not change when other variables change (type of plant, type of fertilizer, amount of sunlight, size of the pots).

Measurement Quantitative information consists of measurements that represent quantities (something that has magnitude, size, or amount). Qualitative data would be descriptions of your observations.

SI Measurement Scientist use the International System of Units (SI).

SI Base Units There are seven SI base units (meter, kilogram, second, kelvin, mole, ampere, candela). All other SI units are derived from these. Mass is the measure of the quantity of matter (SI unit is the kilogram). Measured by using a balance. Weight is a measure of the gravitational pull on matter and is measured by using a spring scale. The SI unit for length is the meter.

Derived SI Units Derived units are produced by multiplying or dividing standard units. The SI unit for volume is m 3 (1mL = 1cm 3 )

Derived SI Units (2) Density is the ratio of mass to volume, or mass divided by volume (D = m/v). The SI unit for density is kg/m 3. In the lab you will usually see density expressed as g/mL or g/cm 3.

Conversion Factors Ratio derived from the equality between two different units that can be used to convert from one unit to another. Example: In one dollar there are 4 quarters 4 quarters or 1 dollar 1 dollar4 quarters

Scientific Notation Numbers are written in the form M x 10 n, where the factor M is a number greater or equal to 1 but less than 10 and n is a whole number. 65,000 km = 6.5 x 10 4 km (when numbers are written in scientific notation only significant figures are shown) mm = 1.2 x mm

Scientific Notation (2) M is determined by moving the decimal point in the original number to the left or the right so that only one nonzero digit remains to the left of the decimal point. n is determined by counting the number of places that you moved the decimal point. If you moved it to the left, n is positive. If you moved it to the right, n is negative.