The Methods of Science

The Methods of Science Integrated Science 9

Science • Science is a process that uses observation and investigation to gain knowledge about events in nature. • Major categories: • Life science • Living things • Earth Science • Earth • Space • Physical Science • Matter • Energy

Investigating our World • Scientists learn new information about the natural world by performing investigations. • Can be done in a variety of ways: • Observing and recording • Experiments • Using Models • The Scientific Method described the procedure commonly followed in scientific investigations

Scientific Method Six common steps used in investigation State the Problem Gather Information Form a hypothesis Test the hypothesis Analyze Data Draw conclusions Not all steps will be used every time Some steps may be repeated Some new steps may be added The scientific method is not a rigid process

Let’s break it down… • Stating the problem • State the problem in a form of a question • Make sure the question asks something that is testable

Testable Questions Why do people ask questions? To a scientist, what do you think makes a good question? What types of questions do you think aren’t suitable for scientific investigation?

Let’s Break it Down… • Researching and Gathering information • Research is necessary to formulate a reasonable hypothesis • Sources of information: • Textbook • Articles • Expert • Reference books • Observations

Let’s break it down…(cont) • Forming a hypothesis • Make an educated guess to answer the question you are investigating • Scientists frequently create a hypothesis with little or no information • As data is collected, a hypothesis is often refined • Testing the hypothesis • Experiments or observation • Experiments • Have only 1 independent variable • All other variables are held constant

Let’s Try That… • An experiment is set up to determine what factor causes the greatest amount of liquid to evaporate. • Three containers of the same size each contain 100 mL of boiling water. • One container is steel, one is brass, and the third is aluminum. • The containers are allowed to sit for 20 minutes. • What is the independent variable? • How many controlled factors are there?

Let’s break it down…(cont) • Analyzing Data • Using tables and charts • Share data with others • Draw conclusions • Does the data support the hypothesis? • What do I need to do now? • Rules of Thumb: • Don’t jump to conclusions • The simplest solution is usually correct

Now we’ll put it all together… In 1912, farmers in California found that it was cheaper to pick all the oranges at once regardless of whether they were ripe. The oranges were placed in a small room heated with kerosene lamps and the oranges would ripen in a few days. At some point, the farmer used an electric heater instead of kerosene lanterns. The oranges no longer ripened. When switching back to kerosene, the oranges ripened. This was found to be true of other citrus. The farmers wondered what was so special about the kerosene lanterns?

Here we go… • What is the question? • What type of research would you do? • Design an experiment. • What is the independent variable? • What are the controlled factors? • Analyze the results • Draw a conclusion

Observations Test Your Observation Skills M&M Lab Variables Worksheet

Visualizing with Models Dams and Levees Cowpea Mosaic Virus Sometimes when observing something that is too large, too small, or too time consuming, we need to use models Models have been used frequently throughout history. Models can be something you can touch or many models are created using computers.

Scientific Theories and Laws • A theory is an explanation of things or events based on knowledge gained by many observations and investigations • Strongly supported hypotheses can become theories • Scientific Laws are statements of what happens in nature • Laws do not offer explanation as to why • Theories Explain Laws!

Standards of Measurement • SI (International System of Units) is the share language for measurement in science • Based on the metric system • Uses multiples of 10 • Each type of measurement has a base unit • Lengthmeter • Masskilogram • Timesecond • Electric currentampere • Temperaturekelvin • Amount of a substancemole • Intensity of lightcandela

SI Prefixes • The SI base units are not always of convenient size for a particular measurement. • The meter would be too big for reporting the thickness of this page • The meter would be too small for the distance from Chicago to Detroit • SI includes a series of prefixes, each of which represents a power of 10. • These allow us to reduce or enlarge the SI base units to convenient sizes.

Conversions Conversions Metric Conversion Ladder • A box weighs 1.25 kg. How many grams is that? • Kilogram (kg) is larger than gram (g) • You need to multiply (shift decimal to the right) • 3 steps (3 zeros) • 1.25 x 1000 = 1,250 grams

Let’s try a few… Conversion Worksheet

Measuring Distance • Choose a unit of length that is appropriate for what you are measuring • For example, • cm for length of pencil • m for length of classroom • Helps avoid using large digit numbers

Measuring Volume The amount of space an object occupies is volume. Measure length, width, and height and multiply the three numbers length x width x height = volume Example: 10 cm x 10 cm x 10 cm = 1000 cm3 Remember: You have to multiply the numbers AND the units Liquid volume is often measured in liters 1 mL = 1 cm3 1000 cm3 is 1000 mL

Measuring Matter • Matter is anything that has mass and takes up space. • To measure mass, we use mass and volume. • Mass and volume can be expressed as a ratio called density • Density is a combination of two SI units. • Combining two or more SI units results in a derived unit. • Can you think of other examples?

Accuracy and Precision • Accuracy • Accuracy is how close a measured value is to the actual (true) value. • Correctness • Precision • Precision is how close the measured values are to each other. • Repeatability

Communicating with Graphs • Scientists often use graphs and charts to display their result in order to better identify patterns • Graphs are useful for displaying numerical information. • Different graphs are useful for different types of information • Line Graph • Bar Graph • Circle Graph

Line Graphs Line graphs are useful whenever a dependent variable is changing due to a change in a independent variable Dependent variables are y-axis Independent variable are the x-axis

Bar Graphs Bar graphs are useful for comparing information collected by counting.

Circle Graphs Circle graph, or pie charts, are use to show how some fixed quantity is broken down The pieces of the pie represent a percentage of the total

The Methods of Science