Scientific Problem Solving Chapter 0

Preview Questions Why is an experiment important? Does experimentation occur in all branches of science? What is scientific inquiry?

0-1: Scientific Inquiry Objectives: Identify steps used during scientific inquiry Explain what results should be gained through scientific inquiry Define critical thinking 0-1: Scientific Inquiry

Understanding Science Science: the investigation and exploration of natural events and the new information that results from these investigations Everyone does this to some extent in their everyday life!

Branches of Science Physical science Physics & chemistry Study of matter and energy What would be some questions one might ask?

Branches of Science Earth science Processes that occur on and within Earth Also includes space science What would be some questions one might ask?

Branches of Science Life science Study of organisms and their processes What would be some questions one might ask?

What is Scientific Inquiry? Scientific investigations are usually to find out more about the natural world Scientific inquiry is a set of skills and tools to answer questions or to test ideas These skills can be used in any order See page NOS 6

What is Scientific Inquiry? Ask Questions Observations often lead to questions—WHY? HOW? Observations are the result of using one or more of your senses to gather information and taking note of what occurs An inference is a logical explanation of an observation drawn from prior knowledge or experience—NOT directly observed

What is Scientific Inquiry? Hypothesize and Predict A hypothesis is a possible explanation for an observation that can be tested by scientific investigation The possible answer to a question A prediction is a statement of what will happen next in a sequence of events Based on previous knowledge and observation

What is Scientific Inquiry? Test Hypothesis and Analyze Results Researching to find prior knowledge Designing an experiment to test your hypothesis Then go over data gathered to analyze your information See if your data supports your hypothesis Remember that the scientific method is not linear; you may have to go back and revise parts of your inquiry!

What is Scientific Inquiry? Draw Conclusions A conclusion is a summary of the information gained from testing your hypothesis Results should be tested and retested many times before you can be certain!

What is Scientific Inquiry? Communicate Results I will argue that this is the most important step: let others know what you learned! Other scientists will evaluate your work and test it There are MANY ways to communicate information

What is Scientific Inquiry? Unsupported or Supported Hypotheses If the hypothesis is not supported, does that mean the experiment was a failure? Why or why not? Think back to the goal of science

Scientific Theory When hypotheses are supported through many tests and time, they can be considered a scientific theory Explanation of observations or events Based on knowledge gained from many observations and events Often connects many hypotheses together Despite being called a “theory”, it is the closest thing to “fact” that we have

Scientific Law A scientific law is a rule that describes a repeatable pattern in nature States what will happen, but does not explain it What is the difference between laws and theories?

Results of Scientific Inquiry WHY DO WE SCIENCE? Develop new materials and technology Technology: The practical use of scientific knowledge Make new discoveries Answer questions

Evaluating Scientific Information What is “scientifically proven”? Is there ever misinformation given out to the public? How do we know what is right and what isn’t? We need to use our critical thinking skills Comparing what you already know with the information you are given

Evaluating Scientific Information The fun part of science is that facts are facts, regardless of someone’s opinion Look at the bottom of page NOS 10

Evaluating Scientific Information Can science answer all questions? Science cannot answer questions that deal with beliefs, values, personal opinions, and feelings What are some examples of questions science CAN answer? What are some examples of questions science CANNOT answer?

Review Key Concepts Vocab What are some steps used during scientific inquiry? What are the results of scientific inquiry? What is critical thinking? Science Observation Inference Hypothesis Prediction Scientific theory Scientific law Technology Critical thinking

0-2: Measurement and Scientific Tools Objectives: Explain why scientists created the International System of Units (SI) Explain why scientific notation is a useful tool for scientists Demonstrate how tools, such as graduated cylinders and triple-beam balances, assist physical scientists 0-2: Measurement and Scientific Tools

Description and Explanation Descriptions are spoken or written summaries of observations Explanations are interpretations of observations Know the difference!

The International System of Units 1960: Scientists decided they needed to use a worldwide standard for measurements in order to achieve better global accuracy This system is called the International System of Units (SI)

The International System of Units Base units are what basic measurements can be found with Derived units (such as g/mL, m3) are based on the base units Prefixes help larger and smaller measurements be easier to read by acting as factors of 10 See chart on NOS 13—KNOW THIS CHART

Measurement and Uncertainty What is the difference between precision and accuracy?

Measurement and Uncertainty What is the difference between precision and accuracy? Precision is how similar repeated measurements are to each other Accuracy is how close a measurement is to an accepted value See pg. NOS 14

Measurement and Uncertainty All tools have some room for error Some tools can give more precise and accurate measurements than others Why do you think a graduated cylinder is more accurate than a beaker? We can estimate slightly beyond what is known

Measurement and Uncertainty Scientific Notation Sometimes we work with REALLY big or REALLY small numbers Scientific notation makes numbers easier to read Also helps reduce errors when counting zeroes

Measurement and Uncertainty Practice! Convert the following to scientific notation: 100 000 0.000 000 003 152 000 000 0.000 034 56 Convert the following from scientific notation: 3×108 5×10−4 6.7×105 9.8×10−9

Measurement and Uncertainty Percent Error There is no such thing as the “perfect experiment”; the goal is to reduce the error as much as possible Percent error tells us how close to the expected results you are Practice on pg. NOS 15

Scientific Tools What are some common tools used by scientists?

Review Key Concepts Vocab Why did scientists create the International System of Units (SI)? Why is scientific notation a useful tool for scientists? How can tools, such as graduated cylinders and triple-beam balances, assist physical scientists? Description Explanation International System of Units (SI) Scientific notation Percent error

0-3: Case Study Objectives: Explain why evaluation and testing are important in the design process Describe how scientific inquiry is used in a real-life scientific investigation 0-3: Case Study

The Minneapolis Bridge Failure August 1, 2007: A bridge for Interstate 35W in Minneapolis, MN collapsed suddenly over the Mississippi River during rush hour Scientists and the public wanted to know why this bridge collapsed

The Minneapolis Bridge Failure

Controlled Experiments Investigators were called upon to determine what caused this collapse They needed to use scientific inquiry to determine the problem They developed controlled experiments Tests how a single factor affects another

Controlled Experiments Identifying Variables and Constraints The first step is to find all of the variables, or factors that can have more than one value that can affect the outcome The independent variable is the factor you want to test—only ONE at a time! Changed by the scientists performing the experiment The dependent variable is the factor you are observing or measuring during the experiment Seeing if it responds to the change Constants do not change in the experiment

Controlled Experiments Experimental Groups An experimental group is used to study how an independent variable affects a dependent variable The control group contains the same factors as the experimental group, but the independent variable does not change

Simple Beam Bridges There are different types of bridges that can be used to cross spans Simple beam bridges have one horizontal beam across two supports Simple and cheap, but will sag in the middle over long distances

Truss Bridges Supported only at ends Assembly of interconnected triangular “trusses” to build strength Beams and supports come together at gusset plates The I-35W bridge is an example of this

Bridge Failure Observations After victims were freed, the bridge was labeled where each part was found Pieces were moved to a park and placed in their relative assembled positions to determine where breaks occurred A video showing the collapse allowed scientists to determine where the collapse began

Asking Questions What are some questions scientists might ask about why it failed?

Asking Questions What are some questions scientists might ask about why it failed? Was the original design faulty? Were there problems with maintenance and repair? Was there too much weight on the bridge? Could it be more than one factor?

Asking Questions Gathering information and data Qualitative data uses words to describe Quantitative data uses numbers to describe Investigators began gathering both kinds of data on the bridge Bridge was built in 1967

Asking Questions Gathering information and data 1977—engineers noticed that salt used for deicing was weakening reinforcement rods Added a thicker layer of concrete, adding about 13.4% more “dead load” (weight from the structure itself; temporary loads such as cars are “live loads”) 1998—further upgrades to boost safety increased the dead load by another 6.1%

Asking Questions An Early Hypothesis During the collapse, there were some renovations occurring on the bridge Four piles of sand, four piles of gravel, a 11,000 L water tanker, a cement tanker, a concrete mixer, and various other supplies were present, increasing the load by 20% (plus the usual traffic) Hypothesis: the bridge failed because it was overloaded

Asking Questions Computer Modeling We don’t have a second bridge to test on (and wouldn’t want to if we did), so how do we test this? Computer modeling allows us to simulate and analyze the situation Determined that the bridge was not overloaded

Asking Questions Revising the Hypothesis Proving the original hypothesis wrong, scientists went back to observations In 1999 and 2003, evaluations, including pictures, were taken on the bridge The eleventh gusset plate was revealed to have been bowing, indicating a problem with the gusset plate that the inspectors and engineers missed

Asking Questions Revising the Hypothesis The investigators found that some gusset plates were fractured, while others were intact Gusset plates are meant to be the strongest points—none should fail Some plates failed very early in the collapse Formed a new hypothesis that the bridge collapsed because the gusset plates failed

Asking Questions Testing the Hypothesis Investigators knew the load limits Calculated the load at the time of collapse and divided it by the load to determine the demand-to-capacity ratio to determine the structure’s safety

Asking Questions Analyzing Results Found that the demand-to-capacity ratio was particularly high on the eleventh gusset plate The plate was about half of the thickness it needed to be

Asking Questions Drawing Conclusions Over the years, modifications added more weight to the bridge Traffic and construction added more load If the gusset plate was designed properly, it would have held the load Could not find any detailed gusset plate specifications in bridge plans Therefore, could not conclude why the gusset plate was wrong, only that it could not hold up the bridge

Asking Questions Results were published by the Federal Highway Administration and the National Transportation Safety Board This provides scientists and engineers with information to help in future bridge designs Communication!

Review Key Concepts Vocab Why are evaluation and testing important in the design process? How is scientific inquiry used in a real-life scientific investigation? Variable Constant Independent variable Dependent variable Experimental group Control group Qualitative data Quantitative data