Unit 1: Energy and Motion Table of Contents 1 Unit 1: Energy and Motion Chapter 1: The Nature of Science 1.1: The Methods of Science 1.2: Standards of Measurement 1.3: Communicating with Graphs

The Methods of Science 1.1 What is Science? Science is a method for studying the natural world. It studies natural patterns. Nature follows a set of rules. Scientists ask questions to learn about the natural world. It is a process that uses observation and investigation to gain knowledge about events in nature. What are some rules that nature follows? gravity, object permanence, What is the difference between natural patterns and nature’s rules? Pattern is what often happens. Rules are laws that govern the patterns. Patterns can have exceptions; not rules.

Major Categories of Science The Methods of Science 1.1 Major Categories of Science Science can be classified according to three main categories. Life science deals with living things. Earth science investigates Earth and space. Sometimes, a scientific study will overlap the categories. Consider the trainer for this runner. --He obviously would need to understand the human body and its systems. --He also would want to understand forces, in order to perfect her stride/running form. --Finally, when considering an optimal diet for an athlete, it’s helpful to understand food and where it comes from and how its grown (ex, genetically modified). Physical science deals with matter and energy.

Science Explains Nature The Methods of Science 1.1 Science Explains Nature Scientific explanations help you understand the natural world. As more is learned about the natural world, some of the earlier explanations might be found to be incomplete or new technology might provide more accurate answers.

Science Explains Nature The Methods of Science 1.1 Science Explains Nature In the late eighteenth century, most scientists thought that heat was an invisible fluid with no mass. Scientists observed that heat seemed to flow like a fluid.

The Methods of Science 1.1 Investigations Scientists learn new information about the natural world by performing investigations, which can be done in many different ways. Some investigations involve simply observing something that occurs and recording the observations.

The Methods of Science 1.1 Investigations Other investigations involve setting up experiments that test the effect of one thing on another. Some investigations involve building a model that resembles something in the natural world and then testing the model to see how it acts.

Scientific Method

The Methods of Science 1.1 Scientific Methods An organized set of investigation procedures is called a scientific method. Six common steps found in scientific methods are shown.

The Methods of Science 1.1 Stating a Problem Many scientific investigations begin when someone observes an event in nature and wonders why or how it occurs. Then the question of “why” or “how” is the problem. Sometimes a statement of a problem arises from an activity that is not working.

Researching and Gathering Information The Methods of Science 1.1 Researching and Gathering Information Before testing a hypothesis, it is useful to learn as much as possible about the background of the problem. Why is this a good idea? Someone else might have done the work and found the answer for you! Or, they might at least start you off further. Or help you avoid problems. (psu -> dc power source) Isaac Newton was one of the greatest scientists of his time. He made great breakthroughs in almost every discipline. Probably one of the smartest people ever to live. He said this: “If I have seen further, it is by standing on the shoulders of giants.” what do you think he meant by that? He made this saying famous, but the idea of it was around before him. This picture is derived from Greek mythology, where the blind giant Orion carried his servant Cedalion on his shoulders.

The Methods of Science 1.1 Forming a Hypothesis A hypothesis is a possible explanation for a problem using what you know and what you observe. For example, NASA scientists hypothesized that a ceramic material might withstand the heat and forces of reentry and could work on the space shuttle. Your hypothesis must be testable. You can test it by direct observation, or by making a model and seeing what happens when you run the simulation. Which do you think is more accurate? direct observation So why would you ever do the model? If you can’t do the experiment, or it’s impractical. NASA would have done this with its ceramics. You can also do both. Model first, then if it works, move on to full-blown direct version.

The Methods of Science 1.1 Testing a Hypothesis One common way to test a hypothesis is to perform an experiment. An experiment tests the effect of one thing on another using controlled conditions.

The Methods of Science 1.1 Variables A variable is a quantity that can have more than a single value. You might set up an experiment to determine which of three fertilizers helps plants to grow the biggest. Try to think of all the variables in this experiment – because you as the experimenter have to account for each one. plant type, sunlight (amount and type: direct vs indirect), amount of water, room temperature, type of soil, and type of fertilizer.

The Methods of Science 1.1 Variables In this experiment, the amount of growth is the dependent variable because its value changes according to the changes in the other variables. It is always measurable. Plant Amount of Water Amount of Sun Fertilizer Type Height after two weeks A 4 oz. every three days 6hr/day 16cm B 14cm C 18cm D none 10cm

The Methods of Science 1.1 Variables The variable you change to see how it will affect the dependent variable is called the independent variable. Plant Amount of Water Amount of Sun Fertilizer Type Height after two weeks A 4 oz. every three days 6hr/day 16cm B 14cm C 18cm D none 10cm

Constants and Controls The Methods of Science 1.1 Constants and Controls A factor that does not change when other variables change is called a constant. Plant Amount of Water Amount of Sun Fertilizer Type Height after two weeks A 4 oz. every three days 6hr/day 16cm B 14cm C 18cm D none 10cm It is best to have only one independent variable; the rest should be standardized, or controlled. sunlight and water are given on the chart, but temperature, soil, and type of plant should also be held constant. Why should you have only one independent variable?

Constants and Controls The Methods of Science 1.1 Constants and Controls The fourth plant is not fertilized. This plant is a control. A control is the standard by which the test results can be compared. Plant Amount of Water Amount of Sun Fertilizer Type Height after two weeks A 4 oz. every three days 6hr/day 16cm B 14cm C 18cm D none 10cm Why is it important to have a control? In this experiment, it looks like the fertilizers work pretty well. But suppose the unfertilized plant grew 25cm. In that case fertilizers would be hurting the plant, so it wouldn’t even matter what the best one was! Science is full of surprises – the greatest discoveries are often unexpected. So you have to always be open to things you may not see coming.

Summary: How can you tell what variable it is? Independent = you control Dependent = measurable outcome Controlled/standardized/constant = the same between groups (Control group = what happens normally, with no independent variable)

Test your new knowledge! Jerry’s Hamster Cheese-a-Thon Results Cheese Time Cheddar 400s Brie 360s Gouda 280s No Cheese 120s Jerry had a hamsters and wanted to know what kind of cheese it liked best. He got 3 different kinds of cheese – cheddar, brie, gouda – and dangled the cheese in front of it while it ran on its hamster wheel. He then measured how long it ran until it gave up. Finally, he measured how long it ran with no cheese in the wheel. IV? Type of cheese DV? Time till quit. SV? Same hamster, same wheel. Control? No cheese. <click> Here are the results. Based on this data, Jerry’s conclusion is that cheddar is the mouse’s favorite. But is this accurate? What is a potential problem? The mouse gets more tired each time! How could this experiment be improved? Do it on different days.

Students of different ages were given the same jigsaw puzzle to put together. They were timed to see how long it took to finish the puzzle. What was the likely question / problem? how does age effect cognitive power? (using puzzle as an indicator) what else could have been used instead of a puzzle? What is the DV? time for puzzle completion What is the IV? age. Tricky, you can’t control age directly, but you can control the people admitted to your study. It’s indirect. Standardized variables? same puzzle. Same room? Same race? Same gender? What was the hypothesis? trick question. We don’t know. The hypothesis is the experimenter’s guess as to what will happen.

The higher the temperature of water, the faster an egg will boil. What is the hypothesis here? this is the hypothesis! What question / problem is it addressing? Imagine what the experiment would be. IV? Temp. DV? Time to boil. SV? Type of egg. Same pot. Same stove. Same altitude above sealevel! Same salt content in water.

The Methods of Science 1.1 Analyzing the Data An important part of every experiment includes recording observations and organizing the test data into easy-to-read tables and graphs. Why is this important? Data must be interpreted. (“the facts don’t lie, but liers use facts.”) If it is not clear, it could be misunderstood and wrong conclusions drawn.

The Methods of Science 1.1 Drawing Conclusions Based on the analysis of your data, you decide whether or not your hypothesis is supported. For the hypothesis to be considered valid and widely accepted, the experiment must result in the exact same data every time it is repeated.

Applications

The Methods of Science 1.1 Being Objective A bias occurs when what the scientist expects changes how the results are viewed. confirmation bias is a tendency to search for, or interpret, information in a way that confirms one's preconceptions, leading to statistical errors This expectation might cause a scientist to select a result from one trial over those from other trials.

The Methods of Science 1.1 Being Objective Scientists can lessen bias by running as many trials as possible and by keeping accurate notes of each observation made. Valid experiments also must have data that are measurable. For example, a scientist performing a global warming study must base his or her data on accurate measures of global temperature.

Video: Awareness Test (to demonstrate a blind trial, which is next slide)

Blind trial A blind or blinded experiment is where information is purposely concealed from the test subject, so that it will not lead to bias or skew the results. If the that information is also concealed from the person giving the test, it’s called double-blind. Basically, the subject of the experiment doesn’t know what’s really going on.

Placebo effect A placebo is a “fake” substance that the test subject believes is real. It is used as a control group, to test for purely psychological effects. Commonly used in medicinal studies, often in the form of a sugar pill.

Video: placebo effect

Other 1.1 The experiment must include a large enough sample size. The Methods of Science 1.1 Other The experiment must include a large enough sample size. The experiment must be repeatable. Findings are supportable when other scientists perform the same experiment and get the same results. Fleischmann and Pons sample size: the one or two test subjects you use might be exceptions. Repeatable: you could have just gotten lucky. Fleischmann and Pons caused a stir when they announced they had discovered a way to perform nuclear fusion at room temperature. But their work was unable to be replicated, and they were heavily criticized.

Visualizing with Models The Methods of Science 1.1 Visualizing with Models A model represents an idea, event, or object to help people better understand it. Sometimes you can’t see everything you’re testing. It might be too large, too small, or takes too much time to see completely.

Models in History 1.1 Light with pudding? The Methods of Science Lord Kelvin, who lived in England in the 1800s, was famous for making models. To model his idea of how light moves through space, he put balls into a bowl of jelly and encouraged people to move the balls around with their hands. Kelvin’s work to explain the nature of temperature and heat still is used today.

High-Tech Models 1.1 Another type of model is a simulator. The Methods of Science 1.1 High-Tech Models Another type of model is a simulator. NASA experiments involving space flight would not be practical without computers. Space camp simulations.

Scientific Theories and Laws The Methods of Science 1.1 Scientific Theories and Laws A scientific theory is an explanation of things or events based on knowledge gained from many observations and investigations. It is not a guess. Just because a scientific theory has data supporting it does not mean it will never change.

Scientific Theories and Laws The Methods of Science 1.1 Scientific Theories and Laws A scientific law is a statement about what happens in nature and that seems to be true all the time. Laws tell you what will happen under certain conditions, but they don’t explain why or how something happens. Gravity is an example of a scientific law .

Scientific Theories and Laws The Methods of Science 1.1 Scientific Theories and Laws Theory vs law: what’s the difference? A theory can be used to explain a law. For example, many theories have been proposed to explain how the law of gravity works.

The Limitations of Science The Methods of Science 1.1 The Limitations of Science What falls in the “realm of science”? Science can help you explain many things about the world, but science cannot explain or solve everything. Most questions about emotions and values are not scientific questions. You might take a survey to get people’s opinions about such questions, but that would not prove that the opinions are true for everyone.

Using ScienceTechnology The Methods of Science 1.1 Using ScienceTechnology Technology is the application of science to help people. For example, when a chemist develops a new, lightweight material that can withstand great amounts of heat, science is used. When that material is used on the space shuttle, technology is applied.

Using ScienceTechnology The Methods of Science 1.1 Using ScienceTechnology Science and technology do not always produce positive results. The benefits of some technological advances, such as nuclear technology and genetic engineering, are subjects of debate. Ex. Stem cells

Review

Question 1 Answer 1.1 What are the three main categories of science? Section Check 1.1 Question 1 What are the three main categories of science? Answer The three main categories of science are life, earth, and physical.

Question 2 Answer 1.1 What is a common way of testing a hypothesis? Section Check 1.1 Question 2 What is a common way of testing a hypothesis? Answer A common way to test a hypothesis is to perform an experiment.

Question 3 1.1 Which of the following is the group in an Section Check 1.1 Question 3 Which of the following is the group in an experiment in which all conditions are kept the same? A. standard B. independent variable C. experimental D. control

What part of the Scientific Method is this What part of the Scientific Method is this? “The temperature of water was measured at different depths of a pond.” What part of the Sci Method is this? the experiment!

What is a blind trial? Why is it done? What is a double-blind trial? What is the placebo effect?