grade 8: life science 2 unit 8l.2 circulation 8 hours · pdf file167 | qatar science scheme of...

167 | Qatar science scheme of work | Grade 8 | Unit 8L.2 | Life science 2 © Education Institute 2005

Grade 8: Life science 2

Circulation

About this unit This unit is the second of six units on life science for Grade 8.

This unit is designed to guide your planning and teaching of lessons on life science. It provides a link between the standards for science and your lesson plans.

The teaching and learning activities should help you to plan the content and pace of lessons. Adapt the ideas to meet your students’ needs. For extension or consolidation activities, look at the scheme of work for Grade 11 and Grade 7.

You can also supplement the activities with appropriate tasks and exercises from your school’s textbooks and other resources.

Introduce the unit to students by summarising what they will learn and how this builds on earlier work. Review the unit at the end, drawing out the main learning points, links to other work and 'real life' applications.

Previous learning To meet the expectations of this unit, students should already know the position in the body and the function of the heart. They should know that cells form tissues and organs. They should be able to relate the functions of specialised cells to their structures. They should be able to recognise that our understanding of science has developed over time and is the work of many countries.

Expectations By the end of the unit, students know the basic structure and function of the human heart and the names and locations of the major blood vessels. They can relate the structure of arteries, veins and capillaries to their functions. They know that scientific work is often done collaboratively, sometimes with colleagues in other countries and they assess the contributions of specific scientists.

Students who progress further describe the structure and function of the human circulatory system.

Resources The main resources needed for this unit are: • model of the heart • software animation showing blood flow through the heart • fresh lamb’s heart (or similar), scalpel and surgical gloves • microscopes and prepared slides of capillaries, veins and arteries • Internet access

Key vocabulary and technical terms Students should understand, use and spell correctly: • atrium, ventricle, capillary, vein, artery • pulmonary artery, pulmonary vein, aorta, vena cava • arteriosclerosis

UNIT 8L.2 8 hours


Standards for the unit

8 hours SUPPORTING STANDARDS CORE STANDARDS

Grade 8 standards EXTENSION STANDARDS

7.7.1 … know that cells are the basic building blocks of organisms and form tissues and organs.

8.8.1 Know the basic structure of the heart and relate this to its function. 11.7.2 Describe the external and internal structure of the heart. Relate features to functions in pumping blood round the body and maintaining separation of oxygenated and deoxygenated blood.

8.8.2 Know the different valves of the heart and how they function.

8.8.3 Know the positions, functions and names of the major blood vessels.

8.8.4 Recognise the differences between arteries, veins and capillaries, and relate their structure to their function.

11.7.5 Differentiate between arteries, veins and capillaries in terms of wall thickness and valves, and relate their structure to their function.

8.8.5 Explain blood pressure and why high blood pressure is an indicator of circulatory problems.

3 hours

Structure and function of heart

3 hours

Circulation and blood vessels

2 hours

Blood pressure

7.2.3 Know that our understanding of science has accumulated and changed over time and is the result of work in many countries.

8.2.2 Assess the importance of the work of specific scientists in developing our understanding of science.

9.2.6 Trace the historical development of some key scientific models and understand the roles of specific scientists in their development.

Unit 8L.2


Activities

Objectives Possible teaching activities Notes School resources

Review with students that the function of the heart is to pump blood. Ask students where this blood is pumped to. Explain that the heart is in fact two pumps joined together, with one side supplying the lungs and the other side supplying the other body organs. Show students a model of the heart and name the four chambers. Hold a diagram of the heart next to a volunteer to show why the left side of the heart is labelled on the right side of the page.

Ask students ‘Why does blood flow one way through each side of the heart?’ Point out the valves between atria and ventricles, and those where blood empties into arteries. Show students an animation or video clip of a heart beating and the direction of blood flow. Provide students with a cross-section diagram of the heart and ask them to label the chambers and valves, and which side has oxygenated and deoxygenated blood.

Prepare student worksheets.

Use this column to note your own school’s resources, e.g. textbooks, worksheets.

If appropriate, dissect a fresh lamb’s heart (or similar) to show the valves attached by strong tendons and the different thickness of different parts of the heart. Ask students why the walls of the ventricles are thicker than the walls of the atria. Ask too why the left ventricle wall is three times as thick as the right ventricle wall and why we can feel our heartbeat on the left side of our chest when it is in the centre. Name the veins and arteries that bring blood to and take it from the heart and ask students to add these labels to their heart diagram.

Ask students to write a set of sentences describing blood flow through the heart, or to put a set of prepared sentences into the correct sequence (e.g. right atrium contracts, right ventricle contracts, blood leaves heart through pulmonary artery, etc.)

Extension activity Ask students to use the Internet to research congenital heart defects and their symptoms and treatment (e.g. hole in the heart, malfunctioning valves).

ICT opportunity: Use of the Internet.

3 hours

Structure and function of heart Know the basic structure of the heart and relate this to its function.

Know the different valves of the heart and how they function.

Assess the importance of the work of specific scientists in developing our understanding of science.

Challenge students to research how our understanding of circulation has developed over time and who they think should be credited with working out how the circulation of the blood works. Tell them to search the Internet using key words such as ‘Ancient China’, ‘Galen’, ‘Ibn Al-Nafis’, ‘Servetus’ and ‘Harvey’. Ask students to consider which scientists based their ideas on evidence and how they collected that evidence. Referring particularly to Ibn Al-Nafis, explain that, even with evidence, it can be difficult to change the accepted explanation of something.


This website provides a useful summary: www.timelinescience.org/resource/students /blood/blood.htm

Unit 8L.2


Objectives Possible teaching activities Notes School resources

Provide students with information and diagrams about veins, capillaries and arteries to label. Ask students to write their own explanations of why capillary walls are so thin, artery walls are elastic and veins have valves. Provide students with a diagram of the double circulation and the names of major veins and arteries.

Encourage students to make up quiz questions to test each other about the names and positions of different arteries and veins (e.g. Which artery carries deoxygenated blood?)

Provide students with diagrams to label.

Ask students to examine prepared slides of capillaries, veins and arteries under a microscope using high and low magnification, or project images of blood vessel structure and discuss as a whole class. Challenge students to construct a table to summarise the similarities and differences between veins, arteries and capillaries (e.g. position in body, function, thickness of wall).

Discuss with students how to recognise the three different types of bleeding that occur depending on what type of blood vessel is injured (e.g. bright red blood spurts from an artery) and what first aid to follow (e.g. apply pressure, elevate injured limb or use a tourniquet).

3 hours

Circulation and blood vessels Know the positions, functions and names of the major blood vessels. Recognise the differences between arteries, veins and capillaries, and relate their structure to their function.

Make sure students appreciate that the pulse is the heart rate and that you can feel your pulse when an artery is near the surface of your skin. Discuss with students why you count your pulse using two fingers rather than your thumb. Encourage students to try to find their own pulse points. Describe several pulse points for students so they can practise finding and counting their pulse (e.g. side of neck, temple of head, wrist and ankle).

Ask students to count their pulse over one minute and then calculate how many times their heart beats in one hour, one day and one year.

2 hours

Blood pressure Explain blood pressure and why high blood pressure is an indicator of circulatory problems.

Define blood pressure as the pressure of the blood against the elastic walls of the arteries. Explain that blood pressure has two values. The higher number represents the pressure while the heart contracts to pump blood to the body. The lower number represents the pressure when the heart relaxes between beats. Blood pressure in a healthy person is normally below 120 over 80 mm Hg.

Provide students with information about high blood pressure, or let them search the Internet for it. Ask them to work in groups to produce a poster that includes: • a definition of high blood pressure; • possible causes (e.g. narrowing of arteries caused by arteriosclerosis); • symptoms; • associated risks (e.g. increased chance of a stroke); • diet and lifestyle changes that can reduce blood pressure.

Challenge each group to deliver a one-minute presentation to the class without hesitation, deviation or repetition. Ask students in the audience to judge whether the group achieved the task and to provide constructive feedback on their presentation.



Assessment

Examples of assessment tasks and questions Notes School resources

a. Label the diagram of the heart.

b. Match the blood vessel to the correct description:

Blood vessel Description

Aorta Carries deoxygenated blood from the heart to the lungs

Pulmonary artery Carries deoxygenated blood from the body to the heart

Vena cava Carries oxygenated blood from the lungs to the heart

Pulmonary vein Carries oxygenated blood from the heart to the body

c. Circulation in mammals is called a ‘double circulation’. Explain what this term means and why a double circulation is needed.

Provide students with a diagram of the heart to label.

Assessment Set up activities that allow students to demonstrate what they have learned in this unit. The activities can be provided informally or formally during and at the end of the unit, or for homework. They can be selected from the teaching activities or can be new experiences. Choose tasks and questions from the examples to incorporate in the activities.

a. The diagram represents the flow of blood to and from a muscle.

i. What type of blood vessel is B?

ii. In the table, tick one box in each row to compare the concentrations of oxygen, glucose and carbon dioxide in blood vessels A and B.

Substance A higher concentration in A than in B

The same concentration in A and in B

A lower concentration in A than in B

Oxygen

Glucose

Carbon dioxide

Unit 8L.2


Examples of assessment tasks and questions Notes School resources

b. Blood flows into and out of all organs.

i. Name the organ represented in the diagram below.

ii. A different organ is represented in the diagram below. Name this organ.

Adapted from QCA Year 9 science test, 1996

grade 8: life science 2 unit 8l.2 circulation 8 hours · pdf file167 | qatar science scheme of...

Documents