Blue's the Clue: Souring Milk for Science (Grades 9-12)
This lab introduces students to the effect temperature has on reducing and controlling the growth of bacteria. Students will use conventionally pasteurized and ultra-high-temperature (UHT) milk to observe how different temperatures (hot, room temperature, cool, and freezing) affect the growth of spoilage bacteria. They will also learn about the importance of pasteurization in keeping food safe.

Background
Lesson Activities
Recommended Companion Resources
Credits
Author
Food and Drug Association (FDA) and National Science Teaching Association (NSTA)
Acknowledgements
The Science and Our Food Supply Curriculum was brought to you by the Food and Drug Administration Center for Food Safety and Applied Nutrition and the National Science Teaching Association.
- FDA Education Team Leader Food Safety Initiative: Marjorie L. Davidson
- FDA Science and Our Food Supply Project Director: Louise H. Dickerson
- FDA/NSTA Associate Executive Director and Science and Our Food Supply Program Director: Christina Gorski
- FDA/NSTA Science and Our Food Supply Program Assistant: Jill Heywood
Option B of the lab activity was adapted by Debra Spielmaker and Utah Agriculture in the Classroom.
Sources
Standards
Texas Content Area Standards
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Principles of Agriculture, Food, and Natural Resources: 130.2.c.1
The student demonstrates professional standards/employability skills as required by business and industry. The student is expected to:
- Principles of Agriculture, Food, and Natural Resources: 130.2.c.1.C: demonstrate knowledge of personal and occupational safety, environmental regulations, and first-aid policy in the workplace.
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Principles of Agriculture, Food, and Natural Resources: 130.2.c.6
The student demonstrates appropriate personal and communication skills. The student is expected to:
- Principles of Agriculture, Food, and Natural Resources: 130.2.c.6.A: demonstrate written and oral communication skills appropriate for formal and informal situations such as prepared and extemporaneous presentations.
- Principles of Agriculture, Food, and Natural Resources: 130.2.c.6.B: demonstrate effective listening skills appropriate for formal and informal situations.
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Principles of Agriculture, Food, and Natural Resources: 130.2.c.7
The student applies appropriate research methods to agriculture, food, and natural resources topics. The student is expected to:
- Principles of Agriculture, Food, and Natural Resources: 130.2.c.7.C: describe scientific methods of research.
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Principles of Agriculture, Food, and Natural Resources: 130.2.c.13
The student describes the principles of food products and processing systems. The student is expected to:
- Principles of Agriculture, Food, and Natural Resources: 130.2.c.13.A: evaluate food products and processing systems.
- Principles of Agriculture, Food, and Natural Resources: 130.2.c.13.C: discuss current issues in food production.
- Principles of Agriculture, Food, and Natural Resources: 130.2.c.13.D: use tools, equipment, and personal protective equipment common to food products and processing systems.
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World Geography Studies: 113.43.d.21
Social studies skills. The student applies critical-thinking skills to organize and use information acquired through established research methodologies from a variety of valid sources, including technology. The student is expected to:
- World Geography Studies: 113.43.d.21.D: analyze information by sequencing, categorizing, identifying cause-and-effect relationships, comparing, contrasting, finding the main idea, summarizing, making generalizations and predictions, drawing inferences and conclusions, and developing connections over time
- World Geography Studies: 113.43.d.21.F: formulate and communicate visually, orally, or in writing a claim supported by evidence and reasoning for an intended audience and purpose
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Economics with Emphasis on the Free Enterprise System and Its Benefits: 113.31.d.21
Social studies skills. The student applies critical-thinking skills to organize and use information acquired through established research methodologies from a variety of valid sources, including technology. The student is expected to:
- Economics with Emphasis on the Free Enterprise System and Its Benefits: 113.31.d.21.A: analyze economic information by sequencing, categorizing, identifying cause-and-effect relationships, comparing, contrasting, finding the main idea, summarizing, making generalizations and predictions, and drawing inferences and conclusions
- Economics with Emphasis on the Free Enterprise System and Its Benefits: 113.31.d.21.F: formulate and communicate visually, orally, or in writing a claim supported by evidence and reasoning for an intended audience and purpose
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Economics with Emphasis on the Free Enterprise System and Its Benefits: 113.31.d.23
Social studies skills. The student uses problem-solving and decision-making skills, working independently and with others. The student is expected to use problem-solving and decision making processes to identify a problem, gather information, list and consider options, consider advantages and disadvantages, choose and implement a solution, and evaluate the effectiveness of the solution.
- Economics with Emphasis on the Free Enterprise System and Its Benefits: 113.31.d.23: Social studies skills. The student uses problem-solving and decision-making skills, working independently and with others. The student is expected to use problem-solving and decision-making processes to identify a problem, gather information, list and consider options, consider advantages and disadvantages, choose and implement a solution, and evaluate the effectiveness of the solution.
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English I: 110.36.c.1
Developing and sustaining foundational language skills: listening, speaking, discussion, and thinking--oral language. The student develops oral language through listening, speaking, and discussion.
- English I: 110.36.c.1.A: engage in meaningful and respectful discourse by listening actively, responding appropriately, and adjusting communication to audiences and purposes;
- English I: 110.36.c.1.B: follow and give complex oral instructions to perform specific tasks, answer questions, or solve problems and complex processes;
- English I: 110.36.c.1.D: participate collaboratively, building on the ideas of others, contributing relevant information, developing a plan for consensus building, and setting ground rules for decision making
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English I: 110.36.c.11
Inquiry and research: listening, speaking, reading, writing, and thinking using multiple texts. The student engages in both short-term and sustained recursive inquiry processes for a variety of purposes.
- English I: 110.36.c.11.A: develop questions for formal and informal inquiry
- English I: 110.36.c.11.I: use an appropriate mode of delivery, whether written, oral, or multimodal, to present results
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English I: 110.36.c.4
Comprehension skills: listening, speaking, reading, writing, and thinking using multiple texts. The student uses metacognitive skills to both develop and deepen comprehension of increasingly complex texts.
- English I: 110.36.c.4.G: evaluate details read to determine key ideas
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English II: 110.37.c.4
Comprehension skills: listening, speaking, reading, writing, and thinking using multiple texts. The student uses metacognitive skills to both develop and deepen comprehension of increasingly complex texts.
- English II: 110.37.c.4.G: evaluate details read to determine key ideas
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English II: 110.37.c.1
Developing and sustaining foundation language skills: listening, speaking, discussion, and thinking--oral language. The student develops oral language through listening, speaking, and discussion.
- English II: 110.37.c.1.A: engage in meaningful and respectful discourse when evaluating the clarity and coherence of a speaker's message and critiquing the impact of a speaker's use of diction and syntax
- English II: 110.37.c.1.B: follow and give complex oral instructions to perform specific tasks, answer questions, or solve problems and complex processes
- English II: 110.37.c.1.D: participate collaboratively, building on the ideas of others, contributing relevant information, developing a plan for consensus building, and setting ground rules for decision making
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English III: 110.38.c.1
Developing and sustaining foundational language skills: listening, speaking, discussion, and thinking--oral language. The student develops oral language through listening, speaking, and discussion.
- English III: 110.38.c.1.A: engage in meaningful and respectful discourse when evaluating the clarity and coherence of a speaker's message and critiquing the impact of a speaker's use of diction and syntax
- English III: 110.38.c.1.B: follow and give complex instructions, clarify meaning by asking pertinent questions, and respond appropriately
- English III: 110.38.c.1.D: participate collaboratively, offering ideas or judgments that are purposeful in moving the team toward goals, asking relevant and insightful questions, tolerating a range of positions and ambiguity in decision making, and evaluating the work of the group based on agreed-upon criteria
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English III: 110.38.c.4
Comprehension skills: listening, speaking, reading, writing, and thinking using multiple texts. The student uses metacognitive skills to both develop and deepen comprehension of increasingly complex texts.
- English III: 110.38.c.4.G: evaluate details read to understand key ideas
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English II: 110.37.c.11
Inquiry and research: listening, speaking, reading, writing, and thinking using multiple texts. The student engages in both short-term and sustained recursive inquiry processes for a variety of purposes.
- English II: 110.37.c.11.I: use an appropriate mode of delivery, whether written, oral, or multimodal, to present results
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English III: 110.38.c.11
Inquiry and research: listening, speaking, reading, writing, and thinking using multiple texts. The student engages in both short-term and sustained recursive inquiry processes for a variety of purposes.
- English III: 110.38.c.11.A: develop questions for formal and informal inquiry
- English III: 110.38.c.11.I: use an appropriate mode of delivery, whether written, oral, or multimodal, to present results
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English IV: 110.39.c.1
Developing and sustaining foundational language skills: listening, speaking, discussion, and thinking--oral language. The student develops oral language through listening, speaking, and discussion.
- English IV: 110.39.c.1.A: engage in meaningful and respectful discourse when evaluating the clarity and coherence of a speaker's message and critiquing the impact of a speaker's use of diction, syntax, and rhetorical strategies
- English IV: 110.39.c.1.B: follow and give complex instructions, clarify meaning by asking pertinent questions, and respond appropriately
- English IV: 110.39.c.1.D: participate collaboratively, offering ideas or judgments that are purposeful in moving the team toward goals, asking relevant and insightful questions, tolerating a range of positions and ambiguity in decision making, and evaluating the work of the group based on agreed-upon criteria
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English IV: 110.39.c.4
Comprehension skills: listening, speaking, reading, writing, and thinking using multiple texts. The student uses metacognitive skills to both develop and deepen comprehension of increasingly complex texts.
- English IV: 110.39.c.4.G: evaluate details read to analyze key ideas
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English IV: 110.39.c.11
Inquiry and research: listening, speaking, reading, writing, and thinking using multiple texts. The student engages in both short-term and sustained recursive inquiry processes for a variety of purposes.
- English IV: 110.39.c.11.A: develop questions for formal and informal inquiry
- English IV: 110.39.c.11.I: use an appropriate mode of delivery, whether written, oral, or multimodal, to present results
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Algebra I: 111.39.c.1
Mathematical process standards. The student uses mathematical processes to acquire and demonstrate mathematical understanding.
- Algebra I: 111.39.c.1.A: apply mathematics to problems arising in everyday life, society, and the workplace
- Algebra I: 111.39.c.1.B: use a problem-solving model that incorporates analyzing given information, formulating a plan or strategy, determining a solution, justifying the solution, and evaluating the problem-solving process and the reasonableness of the solution
- Algebra I: 111.39.c.1.E: create and use representations to organize, record, and communicate mathematical ideas
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Statistics: 111.47.c.1
Mathematical process standards. The student uses mathematical processes to acquire and demonstrate mathematical understanding.
- Statistics: 111.47.c.1.A: apply mathematics to problems arising in everyday life, society, and the workplace
- Statistics: 111.47.c.1.B: use a problem-solving model that incorporates analyzing given information, formulating a plan or strategy, determining a solution, justifying the solution, and evaluating the problem-solving process and the reasonableness of the solution
- Statistics: 111.47.c.1.D: communicate mathematical ideas, reasoning, and their implications using multiple representations, including symbols, diagrams, graphs, and language as appropriate
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Mathematical Models with Applications: 111.43.c.9
Mathematical modeling in social sciences. The student applies mathematical processes and mathematical models to analyze data as it applies to social sciences.
- Mathematical Models with Applications: 111.43.c.9.A: interpret information from various graphs, including line graphs, bar graphs, circle graphs, histograms, scatterplots, dot plots, stem-and-leaf plots, and box and whisker plots, to draw conclusions from the data and determine the strengths and weaknesses of conclusions
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Advanced Quantitative Reasoning: 111.44.c.1
Mathematical process standards. The student uses mathematical processes to acquire and demonstrate mathematical understanding.
- Advanced Quantitative Reasoning: 111.44.c.1.A: apply mathematics to problems arising in everyday life, society, and the workplace
- Advanced Quantitative Reasoning: 111.44.c.1.B: use a problem-solving model that incorporates analyzing given information, formulating a plan or strategy, determining a solution, justifying the solution, and evaluating the problem-solving process and the reasonableness of the solution
- Advanced Quantitative Reasoning: 111.44.c.1.E: create and use representations to organize, record, and communicate mathematical ideas
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Food Technology and Safety: 130.15.c.11
The student describes the processing, packaging, quality analysis, and marketing of milk and dairy products for distribution. The student is expected to:
- Food Technology and Safety: 130.15.c.11.A: describe methods of preparing milk for processing.
- Food Technology and Safety: 130.15.c.11.B: evaluate methods of processing milk and dairy products.
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United States History Studies Since 1877: 113.41.d.31
Social studies skills. The student uses problem-solving and decision-making skills, working independently and with others. The student is expected to:
- United States History Studies Since 1877: 113.41.d.31.B: use problem-solving and decision-making processes to identify a problem, gather information, list and consider options, consider advantages and disadvantages, choose and implement a solution, and evaluate the effectiveness of the solution
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World History Studies: 113.42.d.28
Social studies skills. The student understands how historians use historiography to interpret the past and applies critical-thinking skills to organize and use information acquired from a variety of valid sources, including technology. The student is expected to:
- World History Studies: 113.42.d.28.E: analyze information by sequencing, categorizing, identifying cause-and-effect relationships, comparing, contrasting, finding the main idea, summarizing, making generalizations and predictions, drawing inferences and conclusions, and developing connections between historical events over time
- World History Studies: 113.42.d.28.F: formulate and communicate visually, orally, or in writing a claim supported by evidence and reasoning for an intended audience and purpose
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World History Studies: 113.42.d.31
Social studies skills. The student uses problem-solving and decision-making skills, working independently and with others. The student is expected to:
- World History Studies: 113.42.d.31.B: use problem-solving and decision-making processes to identify a problem, gather information, list and consider options, consider advantages and disadvantages, choose and implement a solution, and evaluate the effectiveness of the solution
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Biology: 112.42.c.1
Scientific and engineering practices. The student, for at least 40% of instructional time, asks questions, identifies problems, and plans and safely conducts classroom, laboratory, and field investigations to answer questions, explain phenomena, or design solutions using appropriate tools and models. The student is expected to:
- Biology: 112.42.c.1.A: ask questions and define problems based on observations or information from text, phenomena, models, or investigations
- Biology: 112.42.c.1.B: use scientific practices to plan and conduct descriptive, comparative, and experimental investigations and use engineering practices to design solutions to problems
- Biology: 112.42.c.1.D: use appropriate tools such as microscopes, slides, Petri dishes, laboratory glassware, metric rulers, digital balances, pipets, filter paper, micropipettes, gel electrophoresis and polymerase chain reaction (PCR) apparatuses, microcentrifuges, water baths, incubators, thermometers, hot plates, data collection probes, test tube holders, lab notebooks or journals, hand lenses, and models, diagrams, or samples of biological specimens or structures
- Biology: 112.42.c.1.E: collect quantitative data using the International System of Units (SI) and qualitative data as evidence
- Biology: 112.42.c.1.F: organize quantitative and qualitative data using scatter plots, line graphs, bar graphs, charts, data tables, digital tools, diagrams, scientific drawings, and student-prepared models
- Biology: 112.42.c.1.G: develop and use models to represent phenomena, systems, processes, or solutions to engineering problems
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Biology: 112.42.c.2
Scientific and engineering practices. The student analyzes and interprets data to derive meaning, identify features and patterns, and discover relationships or correlations to develop evidence-based arguments or evaluate designs. The student is expected to:
- Biology: 112.42.c.2.D: evaluate experimental and engineering designs
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Biology: 112.42.c.3
Scientific and engineering practices. The student develops evidence-based explanations and communicates findings, conclusions, and proposed solutions. The student is expected to:
- Biology: 112.42.c.3.A: develop explanations and propose solutions supported by data and models and consistent with scientific ideas, principles, and theories
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Biology: 112.42.c.4
Scientific and engineering practices. The student knows the contributions of scientists and recognizes the importance of scientific research and innovation on society. The student is expected to:
- Biology: 112.42.c.4.C: research and explore resources such as museums, libraries, professional organizations, private companies, online platforms, and mentors employed in a science, technology, engineering, and mathematics (STEM) field in order to investigate STEM careers
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Environmental Systems: 112.50.c.1
Scientific and engineering practices. The student, for at least 40% of instructional time, asks questions, identifies problems, and plans and safely conducts classroom, laboratory, and field investigations to explain phenomena or design solutions using appropriate tools and models. The student is expected to:
- Environmental Systems: 112.50.c.1.A: ask questions and define problems based on observations or information from text, phenomena, models, or investigations
- Environmental Systems: 112.50.c.1.B: apply scientific practices to plan and conduct descriptive, comparative, and experimental investigations and use engineering practices to design solutions to problem
- Environmental Systems: 112.50.c.1.D: use appropriate tools such as meter sticks, metric rulers, pipettes, graduated cylinders, standard laboratory glassware, balances, timing devices, pH meters or probes, various data collecting probes, thermometers, calculators, computers, internet access, turbidity testing devices, hand magnifiers, work and disposable gloves, compasses, first aid kits, binoculars, field guides, water quality test kits or probes, soil test kits or probes, 30 meter tape measures, tarps, shovels, trowels, screens, buckets, rock and mineral samples equipment, air quality testing devices, cameras, flow meters, Global Positioning System (GPS) units, Geographic Information System (GIS) software, computer models, densiometers, spectrophotometers, stereomicroscopes, compound microscopes, clinometers, field journals, various prepared slides, hand lenses, hot plates, Petri dishes, sampling nets, waders, leveling grade rods (Jason sticks), protractors, inclination and height distance calculators, samples of biological specimens or structures, core sampling equipment, and kick nets
- Environmental Systems: 112.50.c.1.E: collect quantitative data using the International System of Units (SI) and qualitative data as evidence;
- Environmental Systems: 112.50.c.1.F: organize quantitative and qualitative data using probeware, spreadsheets, lab notebooks or journals, models, diagrams, graphs paper, computers, or cellphone applications
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Environmental Systems: 112.50.c.2
Scientific and engineering practices. The student analyzes and interprets data to derive meaning, identify features and patterns, and discover relationships or correlations to develop evidence-based arguments or evaluate designs. The student is expected to:
- Environmental Systems: 112.50.c.2.D: evaluate experimental and engineering designs
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Environmental Systems: 112.50.c.3
Scientific and engineering practices. The student develops evidence-based explanations and communicates findings, conclusions, and proposed solutions. The student is expected to:
- Environmental Systems: 112.50.c.3.A: develop explanations and propose solutions supported by data and models consistent with scientific ideas, principles, and theories
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Environmental Systems: 112.50.c.4
Scientific and engineering practices. The student knows the contributions of scientists and recognizes the importance of scientific research and innovation on society. The student is expected to:
- Environmental Systems: 112.50.c.4.C: research and explore resources such as museums, planetariums, observatories, libraries, professional organizations, private companies, online platforms, and mentors employed in a science, technology, engineering, and mathematics (STEM) field in order to investigate STEM careers
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Environmental Systems: 112.50.c.7
Science concepts. The student knows the sources and flow of energy through an environmental system. The student is expected to:
- Environmental Systems: 112.50.c.7.D: identify and describe how energy is used, transformed, and conserved as it flows through ecosystems
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Earth Systems Science: 112.49.c.1
Scientific and engineering practices. The student, for at least 40% of instructional time, asks questions, identifies problems, and plans and safely conducts classroom, laboratory, and field investigations to explain phenomena or design solutions using appropriate tools and models. The student is expected to:
- Earth Systems Science: 112.49.c.1.A: ask questions and define problems based on observations or information from text, phenomena, models, or investigations
- Earth Systems Science: 112.49.c.1.B: apply scientific practices to plan and conduct descriptive, comparative, and experimental investigations and use engineering practices to design solutions to problems
- Earth Systems Science: 112.49.c.1.D: use appropriate tools such as a drawing compass, magnetic compass, bar magnets, topographical and geological maps, satellite imagery and other remote sensing data, Geographic Information Systems (GIS), Global Positioning System (GPS), hand lenses, and fossil and rock sample kits
- Earth Systems Science: 112.49.c.1.E: collect quantitative data using the International System of Units (SI) and qualitative data as evidence
- Earth Systems Science: 112.49.c.1.G: develop and use models to represent phenomena, systems, processes, or solutions to engineering problems
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Earth Systems Science: 112.49.c.2
Scientific and engineering practices. The student analyzes and interprets data to derive meaning, identify features and patterns, and discover relationships or correlations to develop evidence-based arguments or evaluate designs. The student is expected to:
- Earth Systems Science: 112.49.c.2.D: evaluate experimental and engineering designs
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Earth Systems Science: 112.49.c.3
Scientific and engineering practices. The student develops evidence-based explanations and communicates findings, conclusions, and proposed solutions. The student is expected to:
- Earth Systems Science: 112.49.c.3.A: develop explanations and propose solutions supported by data and models consistent with scientific ideas, principles, and theories;
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Earth Systems Science: 112.49.c.4
Scientific and engineering practices. The student knows the contributions of scientists and recognizes the importance of scientific research and innovation on society. The student is expected to:
- Earth Systems Science: 112.49.c.4.C: research and explore resources such as museums, planetariums, observatories, libraries, professional organizations, private companies, online platforms, and mentors employed in a science, technology, engineering, and mathematics (STEM) field in order to investigate STEM careers
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Earth Systems Science: 112.49.c.12
Science concepts. The student understands how Earth's systems affect and are affected by human activities, including resource use and management. The student is expected to:
- Earth Systems Science: 112.49.c.12.B: analyze the impact on humans of naturally occurring extreme weather events such as flooding, hurricanes, tornadoes, and thunderstorms
- Earth Systems Science: 112.49.c.12.D: analyze recent global ocean temperature data to predict the consequences of changing ocean temperature on evaporation, sea level, algal growth, coral bleaching, and biodiversity