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## Scientific Method

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**Scientific Method**• Systematic approach used in scientific studies • A logical approach to solving problems by observing and collecting data, formulating a hypothesis, testing a hypothesis, and formulating theories that are supported by data**Scientific Method**• Process used by scientists (everyone/anyone) to determine a solution. • “Method” means there is a consistent and reproducible way of doing something • If you need to determine a solution then you must havea problem.**Steps of the Scientific Method**• Observation • Problem Statement • Background Research • Hypothesis Statement • Experiment / Data Collection • Conclusion Statement**Steps of the Scientific Method**• Hypothesis • Data • Make observations and state the problem 2. Gather information about the problem 3. Form a hypothesis Suggested solution to the problem • Not educated guess because use information from step 2 4. Design/conduct an experiment 5. Gather/analyze data information from an experiment 6. Form conclusion based on data and determine whether hypothesis was correct or incorrect with support data**Types of Observation**• Qualitative Data and observations (QL) • Color, shape, odor, or other physical characteristics • Quantitative Data and observations (QN) • Numerical information such as temperature, pressure, volume, the quantity of a chemical formed**Make Observations!**Qualitative Observations Quantitative Observations Length Volume Mass Temperature Speed Density Any type of measurement • Color • Smell • Texture • Shape • Anything regarding the Appearance**Variable**• What does variable mean? • To change…**Variables**• Independent Variable (IV) • aka manipulated variable • Only ONE!!! • The one the INDividual (YOU) physically change/manipulate • Dependent Variable (DV) • aka the responding variable • Only ONE!!! • The one that changes (or you hope will change) when you change the IV • The one you are collecting data about/measuring • Constant Variables • MANY of these • All the things you want to keep the SAME (do NOT change)**Control (or control group)(same as constant)**• If you are trying to see if fertilizer helps orange trees produce more fruit, what must you know first??? • How many oranges does that tree produce NORMALLY (without fertilizer)? • You will grow a set of trees with fertilizer and you will also grow a set of trees in the SAME are, at the SAME time, in the SAME conditions WITHOUT fertilizer • This gives you a STANDARD (something to compare your results to)**Variables**• You should be able to identify the IV and DV (and what your control should be) from your PS!!!!**Formula:**• If…(state what will be done to the IV), then…(state what is predicted to happen to the DV)**CLASS WORKName That Variable!Control (1):Constants(2)**:Independent (1): Dependent (1):Hypotheses (1): • 1. An experiment that tests how quickly different temperatures will dissolve sugar cubes. • 2. An experiment that explores how different colors of light impact plant growth. • 3. How does the temperature of a chemical reaction change over time?**Experiment**• a planned way to test a hypothesis and find out the answer to the problem statement. • a way to collect data and determine the value of the DV. • compares the IV to the DV. • can only test one DV at a time and change one IV at a time • This is called a CONTROLLED experiment**Experiment**• Variables • Materials and Procedures • Data and Results Section • Include observations (QL and QN) • Pictures/tables/graphs/calculations**Why Do We Use Graphs?**Graphs help us visualize numerical data. • •There are several different types of graphs: • Bargraphs: compare multiple objects • Piegraphs: shows relationships of parts to a whole • Linegraphs: show the relationship between 2 variable**Types of Relationships (between variables)**Direct: as x increases y increases Indirect: as x increases y decreases Constant: as x increases y remains the same**Problem**A suggested solution to the problem Gathering**Conclusion Statement**• Do NOT use 1st person • Me, my, I, we, our, etc… • VERY Objective • a summarization that presents the findings of the experiment, what the data shows, and states if the hypothesis was correct (supported) or incorrect (negated) • Restate PS • Restate HYP • Summarize M&P • Analyze and explain data/results (tables, observations, pictures) • State whether HYP was correct or not and EXPLAIN why • Explain possible errors • Explain ways to improve experiment/research • Explain APPLICATION to biology and society**After we accept a hypothesis, experiment, and draw a**conclusion… • Many conclusions that support each other make up a THEORY • Explanation supported by many, many conclusions • Many conclusions that support each other over a period of time • Atomic Theory • Theory of Relativity • CAN be DISPROVEN • “The world is flat” • SCIENTIFIC LAW • A relationship in nature that is supported by many, many experiments • No exceptions • Law of Gravity**At least 3 trials..**• Accuracy • How close to a measured value a measurement is • capable of providing a correct reading or measurement • 'correct' • A measurement is accurate if it correctly reflects the size of the thing being measured. • Precision • Ability to get the same value more than once (regardless of it is the right value or not) • exact, as in performance, execution, or amount • repeatable, reliable, getting the same measurement each time REPEATABILITLY**This is a precise pattern, but not accurate. The darts are**clustered together but did not hit the intended mark. This pattern is both precise and accurate. The darts are tightly clustered and their average position is the center of the bull's eye. This is a randomlike pattern, neither precise nor accurate. The darts are not clustered together and are not near the bull's eye. This is an accurate pattern, but not precise. The darts are not clustered, but their 'average' position is the center of the bull's eye.**Why must we follow the Scientific Method?**• So our results can be reproduced by others so that they will believe our work! • This is called PEER REVIEW!!! • Your work is reviewed and tested by your peers (other scientists, your classmates, your teacher etc) • Assures precision (you want all your results to be precise….close to the same result EVERY trial…that is why we must do many trials of the same experiment**SI Units**• In science, we need to speak the same language • 1795 • French scientists develop metric system • 1960 • International committee meets to update the system and names it the “SystemeInternationaled’Unites” aka SI**SI Base Units**• Seven SI base units • Base unit • A defined unit in a system of measurement that is based on an object or event in the physical world**Tools of the Trade**• Mass Scale that measures GRAMS not POUNDS • Pounds are used to measure the force of gravity on your mass…we want to measure the amount of STUFF (Matter) in a thing • Temperature thermometer measures the kinetic energy (KE) /movement of particles • Faster moving particle=more (KE)=higher temp (HOT) • Slower moving particles=less (KE)=cooler temp (COLD) • Volume amount of space object takes up… • ruler, measuring tape, etc to measure meters3 (l x w x h) • OR graduated cylinder to measure LITERS • Measure volume at the MENISCUS (curve or dip in the water)**Temperature**• SI unit? • Kelvin • Our thermometers measure Celsius • To convert from Celsius to Kelvin • 0o C + 273 = 273 K • To convert from Kelvin to Celsius • 373 K - 273 = 100o C**SI Derived Units**• Not all quantities can be measured with base units • More than one base unit can be used • Speed limit is measure in…. • MPH • Miles per hour • Which is a combo of what base units? • Length and time**Common derived units we will use**• Speed • Base unit of length and base unit of time • Meters/second • Volume • 3 base units of length • Length x length x length • 1 cm3 = 1 mL • Density • Mass/volume • Ratio that compares mass of an object to its volume • g/cm3 or g/mL**Density**• Density=mass divided by the volume • D=m/V • Gram/L or grams/m3 • How do we figure out volume of odd shaped objects…say a paper clip? • Water Displacement • What happens when you fill up the bath tub to the rim and then get in?**Archimedes Principle**• Measure known amount of water in graduated cylinder and record VOLUME (mL) • This is initial volume (Vi) • Drop in odd shaped object (paper clip) • Record the NEW volume of water • This is final vlume (Vf) • Subtract Vi from Vf to get volume of object (Vo) • Vo = Vf- Vi • Get the mass of the paper clip form the scale • Plug the mass (g) and volume (L) into density formula to figure out the density of the paper clip**Class Work!**• Suppose a sample of aluminum is placed in a 25 mL- graduated cylinder containing 10.5 mL of water. The level of water rises to 13.5 mL. Mass is 25 g. What is the density of the aluminum sample? • What is the volume of a sample that has a mass of 150 g and a density of 5 g/mL?**Kids Hate Doing Math Dittos Christmas Morning**King Henry Died Monday Drinking Chocolate Milk**Do you know this number, 300,000,000 m/sec.?**• Do you recognize this number, 0.000 000 000 753 kg. ? • There has to be an easier way to write these numbers….**Scientific Notation**• Easy way to write very BIG or verysmallnumbers • Uses exponents • a shorter method to express very large or very small numbers • Scientific Notation is based on powers of the base number 10.**The number 123,000,000,000 in scientific notation is written**as : 1.23 x 1011 • The first number 1.23 is called the coefficient. • It must be greater than or equal to 1 and less than 10. • The second number is called the base . • It must always be 10 in scientific notation. • The base number 10 is always written in exponent form. • In the number 1.23 x 1011 the number 11 is referred to as the exponent or power of ten.**To write a number in scientific notation…**• Put the decimal after the first digit and drop the zeroes • 123,000,000,000 • Add 10 and your exponent • Your exponent is however many places you had to move the decimal • Exponent is positive or negative • If the # is VERY small… • The exponent will always be NEGATIVE • If the # is VERY BIG… • The exponent will always be POSITIVE**Scientific Notation Tips**• If the # is VERY small… • The exponent will always be NEGATIVE • If the # is VERY BIG… • The exponent will always be POSITIVE