Grade Level(s):  6-8

Subject(s):  Science

Objectives:

1. The students will learn why plants are green
2. The student will learn the process of  photosynthesis
3. The student will learn about chlorophyll and other leaf pigments
4. The student will learn the parts and functions of a plant cell

Time Frame: Five class periods

Technology Tools/Courseware:  Word processor, Internet (Netscape Navigator 3.0)
.
Day One:  Is Light Necessary for Photosynthesis?

Time :  45 minutes for lab DAY ONE
           10 minutes per day for observation and recording in journal

Objectives:
 
1.  The student will discover what happens to the chlorophyll in a plant when the light source is
      removed.
2.  The student will understand the role of sunlight in photosynthesis.
3.  The student will understand why plants are green.
 

Teacher Notes:

Discuss with the students:

1.  Green plants are producers and manufacture their own food.
2.  This process is called photosynthesis.
3.  Green plant need the following in order to grow and make their own energy and food:

•  minerals
•  water
• sunlight
• chlorophyll
• carbon dioxide

Safety Notes:

Go over lab procedures and warn them to be careful with paper clips and scissors.

Materials:

•  healthy green plants
• cardboard or aluminum foil
• scissors
• paper clips

• Divide the students into groups of four
• Cut out four geometric shapes from the cardboard or aluminum foil such as squares, triangles, or circles (make them large enough to cover 1/2 of a leaf)
• Fasten the shapes to individual leaves with a paper clip
• Leave the plants on a south, west, or east window so they will get plenty of sunlight
• Use journals to make observations beginning each day (include weather notes)
• After four days, remove the geometric shapes from the leaves
• Compare the areas on the leaf that were covered with the shape to the rest of the leaf
• Put the plants back in the windowsill (the geometric shapes have been removed)
• Water the plants when needed
• In one week observe the leaves to see what happens when they are able to get sunlight again

This is an excellent lab for colloborative groups.  All students can participate.

Extensions:

1.  Use the internet to search websites to find out about how plants are raised in greenhouses.
2.  Find out how botonists use light, water, and minerals to increase plant productivity.
3.  Use the internet to find out how hydroponics are used to grow food.
Evaluation/Assessment:

Questions:

• Lab write-up
• Journal entry

Activity One:

Time Frame:  45 minutes

Objectives:

1.  The student will understand the role of chlorophyll in the photosynthetic process.
2.  The student will understand why the green chlorophyll disappears from leaves.
3.  The student will see that there are other plant pigments present in green leaves.
4.  The student will understand why leaves turn various colors in the fall.

Teacher notes:

Safety Concerns:

ADULT SUPERVISION IS REQUIRED. Make sure all directions and procedures are understood before beginning.  Isopropyl rubbing alcohol can be harmful if mishandled or misused.

REMIND STUDENTS NOT TO TASTE OR SNIFF THE ALCOHOL

HAVE STUDENTS WEAR LAB APRONS

TEACHER PROCEDURE:

Chlorophyll Extraction:  TO BE DONE ONE DAY BEFORE THE LAB. THE TEACHER IS TO DO THIS.

• spinach leaves
• 70 % isopropyl alcohol
• one large pan and one small pan or double boiler
• water
• thermometer

• Place spinach in the pan
• Tear the leaves into very small pieces
• Cover the leaves with alcohol and grind the leaves into the alcohol
• Heat in double boiler fashion until the thermometer reaches 150 degrees F
• Heat until the alcohol becomes very dark green
• Let cool then squeeze the leaves, leaving the green solution behind.  Discard leaves
• Place the solution in a sealed container

Materials:

• small jars such as baby food jars
• sealed containers of chlorophyll extract
• coffee filters
• scissors
• pencils
• plain white paper
• droppers
• scissors
• tape
• soda straws

Preassessment:

• Discuss how plants prepare for winter due to seasonal changes due to the days shortening, water shortage, temperature changes, and the abscission layer forming (why leaves turn color in the fall).
• Identify the various plant pigments, their names and colors
• Carotone is orange
• Xanthophyll is yellow
• Chlorophyll A is bright green
• Chlorophyll B is duller green
• Anthocyanin is responsible for bright red and purples
• Tannin is brown
• Review the role of chlorophyll in the photosynthetic process
• Review a diagram of the chloroplast

Student Procedure:
 

• Cut a long thin strop of coffee filter about 1/2 inch wide and about 1/2 inch shorter than the container
• Cut a piece of soda straw long enough to lay on top of the jar
• Place one drop of the chlorophyll solution 1/2 inch from the bottom of the strip of filter paper
• Wrap the top of the strip of filter paper around the straw and secure with tape
• Slowly lower the strip down into the jar until the tip just touches the alcohol
• BE CAREFUL NOT TO GET THE REST OF THE FILTER PAPER SOAKED WITH ANY OF THE ALCOHOL OR GET ANY ON THE SPOT OF CHLOROPHYLL
• Wait 15 minutes
• Observe

• The alcohol will travel up the paper at different distances, bringing the color with it as the alcohol evaporates.

• You should be able to see different shades of green and yellow.

• Remove the strips of paper after they dry and tape them to the piece of white paper to observe more closely

This is a colloborative group activity.  Students will disabilities could make a poster listing the plant pigments and colors.

Extensions:
 
Use the Internet to explore states which have the most spectacular fall foliage. Find out the times, dates and geographic locations of fall foliage "peaks" in the Northeast.

Make a list of various flowers and fruits and list beside them the predominant plant pigments which they contain

• Shine a flashlight through the chlorophyll solution and a prism.  Discuss the results in a discussion of wavelength, light energy, and color.

• Journal entry
• Lab write- up
• Students are to give an overview of photosynthesis.  Write the basic formula, labeling the reactants and the products.
• Students can design an experiment involving seeds and light to see the effect of different types of light on the seed growth and transpiration. See sample.

Objectives:

• The student will demonstrate knowledge plant cell organelles
• The student will be able to label a plant cell
• The student will be able to distinguish a plant cell from an animal cell

Preassessment:  45 minutes
 
Go to the following Internet Site to find out about the plant cell.

Concept Development:

• Discuss the structure and function of a plant cell
• Use transparencies to discuss the cell organelles and their function
• Practice quiz for student understanding on the cell parts: Have them label cell parts and describe function.
• Plant Cell Parts:  cell wall, cell membrane, nucleus, mitochondria, vacuole, chloroplasts, cytoplasm

Time Frame:  45 minutes

Objective:

To simulate cytoplasm and the function of the cell wall.

Teacher Notes:

Safety Notes:  None for this activity

Prior to lab make green gelatin and let it partially set up.

Materials:

• resealable plastic bags (small)
• green gelatin
• objects to represent organelles such as small beans, peanuts, seeds, small balloons, etc.\
• small clear plastic container

• Study a diagram of a plant cell
• Think about the structure and function of each part
• Plan a three dimensional model
• Observe objects provided and use them to represent each cell organelle
• Sketch the model and label each part and what is being used to represent each part such as a peanut could represent the mitochondria and a water- filled balloon could represent the nucleus
• Gently poke the bag.
• When finished, label and refrigerate

• Use journals to describe what happens to the gelatin inside
• Answer the questions in journals
•     Do the bags and the contents have definite shape?
•     Can the shape of the bag be changed?
•     Does the shape stay changed?
•     What helps to keep the shape of the bag?

Time Frame:  45 minutes

Objective(s):

• The student will understand the purpose and function of the cell wall.

• Clear plastic food container
• Gelatin-filled plastic bag

• Take a clear plastic food container and the cell model
• Place the bag inside the container pressing gently so that the plastic bag fits snugly up against the sides

• Journal Entry:
• Record how the shape of the bag now compares with the shape of the container
• If the bag were placed in a different type of container, would it change its shape?

Present different-shaped plastic containers and have students predict how they will affect the shape of a gelatin-filled bag.

• Allow the students to test their predictions
• Have students make posters or other displays to identify cell parts

• Journal Entries
• Quiz the students on cell parts and functions.  Use diagram of choice.

Science:

6.16, 6.24, 6.35, 6.8, 6.13, 6.21, 7.8, 7.9, 7.11, 7.15, 7.21, 8.10, 8.13, 8.21, 8.24, 8.29
 
National Standards

Composed by:  Sara Swisher
                        Barb Wilson
                        Jean Wilson
 
References:
http://ericir.syr.edu/projects/Newton/9/phytosy.html
http://www.domtar.com/arbre/english/start2.htm
http://esg-www.mit.edu:8001/esgbio/ps/psdir.html
http://www.cgs.clemson.edu/leaves.htm
http://www.waterw.com/~science/october.html
http://ampere.scale.uiuc.edu/~m-lexa/cell/cell.html
http://www.visitnh.gov/foliage.html
http://ncnatural.com./-color/
 
 
 

Lesson 1

Lesson 2

Lesson 3

Lesson 4

Lesson 5

Lesson 6

Lesson 7