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1.5: Unit Planning

Difficulty Level: At Grade Created by: CK-12
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Content Overview

Circulation: What is it? Why is it important?

In this activity driven unit, students explore these questions to understand their own cardiovascular systems, how they work, and how to keep them functioning effectively. Students make models of the heart and vessels, examine a mammalian heart, and listen to their own heartbeats to gain background for understanding basic structures of the cardiovascular system. They complete investigations of diffusion to connect the movement of molecules, with the passage of oxygen and nutrients out of capillary beds into the cells, and the passage of wastes and carbon dioxide from cells into the capillaries. By investigating how the body's control system regulates pressure and resistance in the vessels, students are introduced to negative feedback systems and their importance in regulating the cardiovascular system. With this background, students approach the concept of homeostasis, the internal body balance maintained by the circulatory system in the face of changing environmental conditions, and investigates how a healthy circulatory system maintains this balance. Students study risk factors for cardiovascular disease, based on their expanded knowledge of the circulatory system, and consider the evidence from the perspective of making good decisions about cardiovascular health and fitness.

Because the key ideas of the unit build in a spiral manner, it is advisable to complete sections 1-7 in sequence.

How is the unit structured?

Section 1 presents an overview of the circulatory system and an in-depth study of blood and its components.

Section 2 explores the heart's structure and how it functions.

Sections 3, 4, and 5 cover the blood vessels-arteries and arterioles, capillaries, and veins and venules.

Section 6 goes on to discuss pressure, flow and resistance in those blood vessels.

Section 7 covers cardiovascular health and the risk factors which affect it.

Why teach this unit? Connections to the Real World

According to the American Heart Association approximately people die each year from cardiovascular disease. America spent an estimated billion dollars on cardiovascular related health problems in 1997. Approximately, people in the US have one or more forms of cardiovascular disease. (Statistics obtained from the American Heart Association).

How is the unit structured?

PE Figure 1.1 Your circulatory system is like the streets of a city with lots of traffic flowing through the streets to and from different destinations.

PE Figure 2.20 The heart's two pumps work together side by side. Can you trace the flow of blood through the heart?

Rarely can you make it through the day without hearing the words “low-fat,” “healthy,” and “exercise.” Why? Because so much is known about cardiovascular health that our lives are filled with advice on how to keep our hearts healthy. An approach to teaching adolescents to make good decisions about their health is for them to explain the structure and function of their cardiovascular system. The more they know about how their bodies work, the better able they will be to make wise decisions that will lead to a healthy lifestyle.

A big part of choosing a healthy lifestyle involves the assessment and assumption of risk factors. This unit introduces the concept of risk. However, the discussion of risk could-and should-extend beyond food, exercise and the cardiovascular system. Many adolescents feel invulnerable-full of energy but lacking the experience of disease and death. At some point, a few will lose a friend or relative to disease or violence, and their understanding will grow. Risk is an inherent part of every youth's life. This unit provides a good opportunity to help them make decisions that could affect their lives for the long term.

This unit also stresses that cardiovascular health and fitness extend beyond personal choices to important public policy issues. The following summary questions provide a context for discussing cardiovascular health in a broader context:

Summary Questions to Consider throughout the Unit

Why don't more people donate blood or, in the event of premature death, healthy vital organs?

Should all packages of food contain information about possible health effects? For example, should a package of hamburger have a label warning consumers about the effects of eating fatty foods and red meat?

Is risk the same for everyone? How does risk vary from situation to situation?

Section 3: Arteries and Arterioles
Section 4: Capillaries
Section 5: Veins and Venules

PE Figure 5.1: The veins form a network of vessels that return blood to the heart.

Section 6: Pressure, Flow, and Resistance

PE Figure 6.8: This drawing shows how the cuff and stethoscope should be positioned to read the blood pressure.

Section 7: Cardiovascular Health

PE Figure 7.1: When arteries that feed the heart get narrow, the heart muscle doesn't get enough oxygen.

Unit Activities and Key Ideas
Section Key Ideas Activity
1. Circulation
Why is blood important to life?
  • Complex animals like humans depend on the blood to transport food, water, oxygen, carbon dioxide and wastes to and from the body cells.
  • Blood is made up of cells and plasma and blood diseases compromise the efficiency of the blood delivery system.
  • The lymphatic system is a network of vessels and lymph nodes that function to recycle fluids which leak out of blood vessels back to the circulatory system.
Activity 1-1: Pathway of Blood through Your Body
Activity 1-2: Composition of Blood
Mini Activity: Blood Impressions
Mini Activity: Artificial Blood
2. The Heart
How does the heart pump blood?
  • The heart is divided into four chambers: two “pumps” with two chambers each. One pump sends blood to the lungs for oxygen and back to the heart, the other sends the oxygenated blood throughout the body.
  • The cardiac (heart) cycle is made up of a squeeze cycle and fill cycle: squeeze-fill; squeeze-fill; or systole-diastole, systole-diastole.
  • The pacemaker is a specialized region of the heart which in combination with the nervous system and the endocrine system help to maintain homeostasis.
Mini Activity: Is Pumping Hard Work?
Activity 2-1: Exploring the Heart
Mini Activity: Heartbeats
Mini Activity: Word Origins
Activity 2-2: Siphon Pump
Mini Activity: What's Your Cardiac Output Today?
Enrichment 2-1: What Makes the Heart Beat Faster?
3. Arteries and Arterioles
How does blood get from the heart to all parts of the body?
  • Arteries are thick, muscular vessels which carry blood away from the heart. Because arteries are elastic they expand during systole and their contraction during diastole propels the blood through the body.
  • Arterioles are the smallest arteries, and have rings of muscle around them to serve as valves. By relaxing or contracting they control blood flow into the capillaries, and they control blood pressure in the arteries.
  • Arteries and arterioles help maintain blood flow by maintaining blood pressure.
Mini Activity: Taking Your Pulse
Activity 3-1: Blocked Arteries
4. Capillaries
How do oxygen and nutrients get from blood to cells?
  • Capillaries are thin and permeable blood vessels that allow for the exchange of nutrients, gases and waste.
  • This exchange of nutrients, gases and waste occurs through the process of diffusion.
  • The capillary network is extensive; no cell is more than 2 cells away from a capillary.
Activity 4-1: Making a Capillary Bed Model
Mini Activity: Transport of Nutrients: Exploring Diffusion
Enrichment 4-1: Observing Goldfish Capillaries
Enrichment 4-2: Transport of Materials Exploring Diffusion
5. Veins and Venules
How does blood get back to the heart?
  • Veins and venules are the counterparts of arteries and arterioles. They carry blood away from the capillaries Veins back to the heart.
  • The walls of veins are thinner than those of arteries and can expand and collapse according to how much blood is in them.
  • The pressure in veins is lower than the pressure in capillaries, so blood flows in one direction; from capillaries to venules to veins. Valves and the action of muscles help carry blood back one way to the heart.
Mini Activity: Observing Veins
Mini Activity: Percentages of Blood
Activity 5-1: The Direction of Blood Flow
6. Pressure, Flow, and Resistance
How is the right amount of blood directed to each part of the body?
  • Blood pressure is an important indicator of how hard the heart is working to circulate blood through the body. High blood pressure can indicate a health problem.
  • Friction builds up resistance in blood vessels contributing to an elevation of blood pressure.
  • The endocrine and the nervous systems provide feedback that regulates basic functions such as breathing, heart rate and blood pressure.
Activity 6-1: Pressure, Resistance, and Flow
Mini Activity: The You in You
Mini Activity: Cold Toes
Activity 6-2: How a Controller Works
Enrichment 6-1: Your Blood Pressure
7. Cardiovascular Health
How can I keep my heart strong and my arteries clean and clear?
  • Cardiovascular disease is the leading cause of death in this country.
  • Cardiovascular risk factors can be genetic and/or environmental.
  • Making healthy choices can reduce the risk of getting cardiovascular disease.
Mini Activity: Your Target Heart-Rate Zone
Activity 7-1: Pulse Rate
Mini Activity: Sources of Stress
Mini Activity: Risk profile
Enrichment 7-1: Cardiovascular Disease Risk Scoring

Teacher's Guide Overview

This Circulation unit is built around a variety of student activities. Text material can be used to introduce, reinforce, and extend the concepts developed in the activities. The activities are the foundation of this unit, so the unit's success depends on students' involvement in the activities. Embedded activities are interrelated, since the concepts developed in one may be applied in another.

Section Planning

For each section, you'll find extensive advance planning for the student activities and the section topic. Key ideas, section objectives, background information, suggestions for introducing activities, and the materials needed for each activity are listed on the Section Planning page. Review this information ahead of time to ensure that materials for each activity are available when you need them.

Support for Embedded Activities

Embedded activities are those activities contained or “embedded” in the student edition. Procedures for each embedded activity are contained in the student edition. In the Teacher's Guide, you'll find activity planning information, activity assessment, and student reproducible pages for each embedded activity.

Enrichment Activities

Enrichment activities are activities found in the Teacher's Guide. These activities are designed to extend and enrich students' learning experiences. Complete Enrichment activities, including Teacher Activity Notes and the student procedures and reproducible pages, are located at the end of each appropriate section of the Teacher's Guide.

Group Work Activities

Learning science is a process that is both individual and social. Students in science classrooms often need to interact with their peers to develop a knowledge of scientific concepts and ideas, just as researchers, engineers, mathematicians, and physicians who are working in teams do to answer questions and to solve problems. The Group Work activities of the HumBio Curriculum for Middle Grades have been developed to foster a collaborative environment for groups of students. Students plan experiments, collect and review data, ask questions and offer solutions, use data to explain and justify their arguments, discuss ideas and negotiate conflicting interpretations , summarize and present findings, and explore the societal implications of the scientific enterprise. In short, Group Work activities provide an environment in which students are “doing science” as a team.


The research and action projects in HumBio are varied and provide students with time to explore a particular topic in depth. With Projects, students have the opportunity to take a position based on knowledge gained through research, debate an issue, and devise a plan of action. In this way, students can apply what they are learning to larger issues in the world around them.

Projects for this unit include

  • Research Questions and Action Projects
  • Be Heart Smart
  • A Cafeteria Case Study
  • Tasty Tidbits
  • Past vs. Present

Assessment Overview

Within each section of the unit there are suggestions for assessment that can be used individually or in combination to develop a complete assessment package. The list below describes the variety of assessment tools provided.

Apply Your Knowledge Questions appear throughout each section. They can be used as homework assignments and as ways to initiate a class discussion. These Questions are designed to assess

  • communication skills
  • depth of thought and preparation
  • problem-solving skills
  • ability to apply concepts to related or big ideas
  • how well students relate their new knowledge to different problems

What Do You Think?

These Questions appear in each section. They provide students with opportunities to think and write about the concepts they are learning in a larger context. You can use these Questions to assess

  • writing skills
  • problem-solving abilities
  • creativity and depth of thought
  • the ability to analyze and summarize

Journal Writing prompts are suggested throughout the unit. These prompts provide opportunities for students to write critically and creatively about concepts and issues. The writing products can be used to assess

  • writing skills
  • depth of thought
  • and the ability to explain and expand concepts

Review Questions

Review Questions are located at the end of each section. These Questions can be used for written responses or as the basis for class discussion. These Questions are designed to assess content knowledge and whether students can explain the concepts explored in the section.

Activity-Based Assessment

Inquiry-based student-centered activities are the foundation of the Human Biology Program. The unit is rich with relevant exciting activities that introduce, support, or reinforce concepts students are exploring. Within the Teacher's Guide, you'll find extensive teacher Information, including assessment strategies, for each type of activity:

  • Embedded Activities
  • Enrichment Activities
  • MiniActivities
  • GroupWork
  • Projects

You can use students' products to assess their progress. These products include models, simultaneous, observations and reports of laboratory investigations, role plays, written responses to questions and written observations, student-designed explorations and procedures, poster presentations and classroom presentations.


You may want to have your students develop a portfolio for the unit. A sample assessment portfolio for the unit might contain the following items:

  • Written responses to three What Do You Think? questions
  • An analysis of their two favorite Activities and how those activities helped then understand an important concept
  • Two examples of written reports from library research from
Mini Activity: Cold Toes
Mini Activity: Artificial Blood
  • An Activity Report from three investigations such as
Activities 2-1, 2-2, 4-1, 5-1
  • An analysis or interpretation of graphs from Activity 3-1
  • Example of constructing a model from
Activity 4-1: Making a Capillary Bed Model
  • One example of an artistic creation from
Mini Activity: Blood Impressions

Getting Started

The Human Biology Circulation unit emphasizes learning about the structure and function of the circulatory system and how to apply this knowledge to making good decisions about overall cardiovascular fitness.

As with all Human Biology units, the Circulation unit is built around inquiry. For each activity, teacher information is included on the section planning page and the activity page.

Plan the Unit to Fit Class Needs. For each activity, helpful hints, strategies and the materials needed are listed in the Teacher's Guide. Checking this information ahead of time will ensure that the materials will be available when needed. Teacher information for each activity is included in the Plan for each Section under the heading Advance Preparation. The important activity information is also listed in the Activity Planning page under the heading Advance Preparation.

Be aware of any special health problems your students may have which would make it uncomfortable for them to participate in certain activities such as taking measurements of pulse, blood pressure, and heart rates. Examples of such health problems include congenital or accidental cardiovascular conditions. For students unable to participate fully in these activities, you may wish to create an alternative assignment or to have them use data from another group. If the class is prepared appropriately, the affected students may want to share their special circumstances with the class to enhance the appreciation and understanding of all students.

Connect with Other Disciplines. The Circulation unit is particularly well suited for interdisciplinary use in combination with the units on Breathing and Digestion and Nutrition.

Although many schools include this unit through health or science classes, the interdisciplinary web provided shows you ways to expand the teaching of this material into other subject areas to reinforce learning for students. For interdisciplinary planning set meetings with your team early. The suggested interdisciplinary breakdown below provides some ideas for connections among subject areas. You are encouraged to tap the talents and interests of your team members as well as of your unique school and community resources in developing other suitable activities for this unit. Your school library/multimedia resource center and the science department at the high school may also be able to provide references that can be very helpful in teaching this unit.

As previously mentioned, continued emphasis upon healthy decision making leading to improved cardiovascular health involves all body systems affected by the circulatory system. Therefore, this unit is ideal for combining with the Human Biology units on Breathing and Digestion and Nutrition. The Circulation unit also links well with the Human Biology unit on the Nervous System because of the nervous system's role in controlling and coordinating homeostasis in the body.

Connections to other Human Biology units include Genetics with respect to hereditary predisposition to cardiovascular disease.

Use Current Events. Current events can be an important part of the circulation unit. Students can use current events to make group scrapbooks, bulletin boards, posters, or to give class presentations. Some examples of current event topics include articles explaining guidelines for healthy eating and exercise programs, medical advances in treating blocked arteries and heart disease, and information about new medications helpful in controlling high blood pressure.

Make Career Connections. Encourage student investigation of careers related to cardiovascular health such as in research, industrial production of medications, public education, and in health professions. Examples of health professions include a cardiologist, a surgical nurse specializing in cardiology, and a paramedic.

Use a Variety of Resources. For the duration of the unit, we encourage you and your students to use a wide variety of resources. The activities provide rich opportunities for students to explore many concepts, and the more they incorporate information from sources outside the classroom, the richer their experiences will be. Use your own creativity and the student activities in this unit to develop a series of lessons tailored to the needs of your students. Engage students through activities to help them learn about the function, and importance of the circulatory system. Use computer services for student and teacher information, networking (student pen pals, other schools, other teachers, other communities), and connecting with experts in the field.

Plan for Field Trips. Field trips to local hospitals, industrial sites, or universities need to be arranged in advance. Contact the public affairs offices of these institutions for assistance.

Possible guest speakers include specialists from the careers mentioned above.

If you select a guest speaker with a cardiovascular condition to address that condition, be sure to prepare your students appropriately so they will be sensitive and compassionate listeners. Prepare speakers by sharing with them the knowledge base of students.

Connect with the Home. Because lifestyle changes for improving cardiovascular health may involve changes in family eating and exercise patterns, students should be encouraged to take Apply Your Knowledge questions and Mini Activities home for further exploration. As a class, or as individuals, the new questions raised can become a part of ongoing research for everyone.

Teaching Timelines

You can use these timelines as a place to start in designing your own timelines, or you can use them as they are laid out. If you're planning your own timeline, consider the inclusion of the Embedded activities first. The “Embedded activities” are included in the student edition. The Enrichment activities, Group Work activities, and Projects can then be included, depending on your time restrictions. The timelines are guides that can vary if some activities are done at home or in other classes in addition to science class.

Given your time constraints, it may not be possible to do all the activities on these timelines. If you need to remove activities, be careful not to remove any activities critical to sequential student understanding of the unit. You may want to divide the activities among interdisciplinary members of your teaching team.

Page references in these charts refer to the student edition, except when Enrichments are suggested. The page references for Enrichments refer to this Teacher's Guide.

Option 1: Three Week Timeline
Monday Tuesday Wednesday Thursday Friday
Week 1
Introduce Unit
Introduce Section 1
Activity 1-1: Pathway of Blood Through Your Body
Conclude Activity 1-1
Activity 2-1: Composition of Blood
Assign Mini Activities: Blood Impressions Artificial Blood
Introduce Section 2
Activity 1-2: Exploring the Heart
Continue Activity 2-1: Exploring the Heart
Activity 2-2: Siphon Pump
Week 2
Mini-Activities: Heart beats Word Origins What's Your Cardiac Output Today?
Activity 3-1:
Blocked Arteries
Review Sections 1, 2, 3
Introduce Section 4
Teaching Strategies
Enrichment 4-1:
Enrichment 4-2:
Transport of Materials Exploring diffusion
Introduce Section 5.
Activity 5-1: The Direction of Blood Flow
Week 3
Review Sections 3, 4, 5
Introduce Section 6.
Activity 6-1: Pressure, Resistance and Flow
Enrichment 6-1: Your Blood Pressure
Activity 6-2: How a Controller Works
Introduce Section 7
Activity 7-1: Pulse Rate
Assign Mini Activities: Your Target Heart Rate Zone
Risk Profile
Unit Review and Assessment
Option 2: Five Week Timeline
Monday Tuesday Wednesday Thursday Friday
Week 1
Introduce Unit
Introduce Section 1
Activity 1-1: Pathway of Blood Through Your Body
Conclude Activity 1-1
Activity 1-2: Composition of Blood
Conclude Activity 1-2
Assign Mini Activities: Blood Impressions Artificial Blood
Introduce Section 2
Introduce Activity 2-1: Exploring the Heart
Optional Mini Activity: Is Pumping Hard Work?
Activity 2-1: Exploring the Heart
Week 2
Optional Mini Activity: Heartbeats
Assign Mini Activity: Word Origins
Activity 2-2: Siphon Pump
Optional Mini Activity: What's Your Cardiac Output Today?
Enrichment 2-1: What Makes the Heart Beat Faster?
Introduce Section 3
Mini Activity: Taking Your Pulse
Activity 3-1: Blocked Arteries
Review Sections 1, 2, 3
Introduce Section 4
Week 3
Enrichment 4-1:
Enrichment 4-2:
Transport of Material Exploring Diffusion
Introduce Section 5.
Activity 5-1: The Direction of Blood Flow
Mini Activities:
Observing Veins Percentages of Blood
Introduce Section 6
Activity 6-1: Pressure, Resistance, and Flow
Week 4
Mini Activities:
The You in You
Cold Toes
Activity 6-2: How a Controller Works
Enrichment 6-1:
Your Blood Pressure
Review Sections 4,5, 6
Including the Key Ideas
Introduce Section 7
Mini Activities:
Your Target Heart Rate Zone
Sources of Stress
Activity 7-1:
Pulse Rate
Week 5
Mini Activity:
Risk Profile
Enrichment 7-1:
Disease Risk
Project Presentations, Culminating Activities
Unit Reviews
Including Unit Assessment
Project Presentations, Culminating Activities
Unit Reviews
Including Unit Assessment
Project Presentations, Culminating Activities
Unit Reviews
Including Unit Assessment

Safety for Teachers

  • Always perform an experiment or demonstration on your own before allowing students to perform the activity. Look for possible hazards. Alert students to possible dangers. Safety instructions should be given each time an experiment is begun.
  • Wear glasses and not contact lenses. Make sure you and your students wear safety goggles in the lab when performing any experiments.
  • Do not tolerate horseplay or practical jokes of any kind.
  • Do not allow students to perform any unauthorized experiments.
  • Never use mouth suction in filling pipettes with chemical reagents.
  • Never “force” glass tubing into rubber stoppers.
  • Use equipment that is heat resistant.
  • Set good safety examples when conducting demonstrations and experiments.
  • Turn off all hot plates and open burners when they are not in use and when leaving the lab.
  • When students are working with open flames, remind them to tie back long hair and to be aware of loose clothing in order to avoid contact with flames.
  • Make sure you and your students know the location of and how to use fire extinguishers, eyewash fountains, safety showers, fire blankets, and first-aid kits.
  • Students and student aides should be fully aware of potential hazards and know how to deal with accidents. Establish and educate students on first-aid procedures.
  • Teach students the safety precautions regarding the use of electricity in everyday situations. Make sure students understand that the human body is a conductor of electricity. Never handle electrical equipment with wet hands or when standing in damp areas. Never overload electrical circuits. Use prong service outlets.
  • Make sure that electrical equipment is properly grounded. A ground-fault circuit breaker is desirable for all laboratory AC circuits. A master switch to cut off electricity to all stations is desirable for all laboratory AC circuits.
  • Make sure you and your students are familiar with how to leave the lab safely in an emergency. Be sure you know a safe exit route in the event of a fire or an explosion.

For Student Safety

Safety in the Classroom

  • Wear safety goggles in the lab when performing any experiments. Tie back long hair and tuck in loose clothing while performing experiments, especially when working near or with an open flame.
  • Never eat or drink anything while working in the science classroom. Only lab manuals, notebooks, and writing instruments should be in the work area.
  • Do not taste any chemicals for any reason, including identification.
  • Carefully dispose of waste materials as instructed by your teacher. Wash your hands thoroughly.
  • Do not use cracked, chipped, or deeply scratched glassware, and never handle broken glass with your bare hands.
  • Lubricate glass tubing and thermometers with water or glycerin before inserting them into a rubber stopper. Do not apply force when inserting or removing a stopper from glassware while using a twisting motion.
  • Allow hot glass to cool before touching it. Hot glass shows no visible signs of its temperature and can cause painful burns. Do not allow the open end of a heated test tube to be pointed toward another person.
  • Do not use reflected sunlight for illuminating microscopes. Reflected sunlight can damage your eyes.
  • Tell your teacher if you have any medical problems that may affect your safety in doing lab work. These problems may include allergies, asthma, sensitivity to certain chemicals, epilepsy, or any heart condition.
  • Report all accidents and problems to your teacher immediately.


  • Preserved specimens showing signs of decay should not be used for lab observation or dissection. Alert your teacher to any problem with the specimen.
  • Dissecting instruments, such as scissors and scalpels, are sharp. Use a cutting motion directed away from yourself and your lab partner.
  • Be sure the specimen is pinned down firmly in a dissecting tray before starting a dissection.
  • In most cases very little force is necessary for making incisions. Excess force can damage delicate, preserved tissues.
  • Do not touch your eyes while handling preserved specimens. First wash your hands thoroughly with warm water and soap. Also wash your hands thoroughly with warm water and soap when you are finished with the dissection.

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Date Created:
Feb 23, 2012
Last Modified:
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