Exploring the Dimension

As you move along in your career as an educator you may find that some of your students will be asking, “What do I need to learn this for? I’m never going to use it!” There will be concepts you’re required to teach where you may be asking yourself the same thing. Challenges like this make it all the more important for you to understand the Personal and Social Perspectives dimension of science. By exploring this dimension you will learn that when this dimension is built into your science lessons your students will develop an understanding of person health, be able to identify characteristics and describe changes in populations, identify types of resources as well as environments and changes in them, and they will learn to recognize the benefits and challenges of science and technology – that one new advancement can lead to new problems!

The Problem: Can advancements in society occur without causing new problems?

The Task: The Dust Bowl

The United States experienced a recession at the end of World War I. American farmers reacted to a loss in income by increasing their production. Farms were becoming more mechanized so it was easier to produce more, eventually over working the land. The grasslands of the Great Plains were replaced with farmers’ fields. Rich soils lost ground cover and valuable nutrients. Soon erosion became a serious problem as the center of the United States experienced a seven-year drought which began in 1931. By 1932 severe dust storms caused many farms to literally blow away. Many of these farm families, already left destitute by the Great Depression gave up on their dream of farming in “ America’s Bread Basket” and moved their families west to California. What lessons can we learn from the plight of Americans during the Dust Bowl Days so that we can answer YES to The Problem above?

Download the concept map for this segment of the New Dimensions of Science. Review the details for each of the coordinating concepts under Science in Personal and Social Perspectives. These are to: develop an understanding of personal health; identify environments and changes; identify types of resources; identify and describe changes in populations; recognize the benefits and challenges of science and technology.

As you explore the Library of Congress’ American Memory Collection “Voices from the Dust Bowl” collect examples on how each of the aspects of this dimension are evidenced during The Dust Bowl. Be sure to listen to the plight of the people through their songs such as Sunny Cal and their personal stories. Extend the existing concept map by adding your examples from the Dust Bowl Days to the subordinate concepts found on the bottom of the concept map. In the case of events which took place during The Dust Bowl Days how would you answer The Problem posed above: Can advancements in society occur without causing new problems?Have we learned from this tragedy in American History? What changes in farming practices today do you think will prevent the occurrence of future Dust Bowl Days? Email a copy of your new concept map and your response to these questions to your instructor.

Sample Lesson:

Now that you've explored the Science in Personal and Social Perspectives Dimension of Science review the sample lesson below. In fact, you may want to develop an Integrated Science Lesson where you have your students explore the Dust Bowl Days much as you did above, addressing Science and Social Studies Standards within one lesson. By providing your students with that experience you will set the stage for this science exploration on Starches. You could have your students explore the kinds of foods that sustained those affected by The Dust Bowl. Lead them to discover that many subsisted for months on variations of the potato, mashed, fried, and as a soup. As a driving question for this investigation you can ask your students if they could survive on a steady diet of potatoes. Regardless of their responses you could move into this lesson by stating something like – “well while some of you think you couldn’t survive on potatoes alone I’ll just bet that your diets aren’t much different than many of the migrant farmers!” As they look at you puzzled then say something along the lines of “I’m not going to go into details about my comment right now – I’d just like you to think about that statement as we begin an exploration of starch grains.” The end of this lesson provides questions which will help the learners understand why you made that statement.

Future Teachers:

Go to your state learning standards for science. Determine which standards are made concrete through this lesson. Submit your ideas for the standards to your instructor. Go through this lesson as if you are a student in the given grade level. As you participate in the exploration phase of the lesson see if you can determine what concept or concepts will be made concrete during the explanation phase. Once the class has completed the entire lesson we will revisit your suggested standards. Questions we will discuss about this lesson include:

• Which of the standards you selected were made concrete through your participation in this lesson?
• From the standards you selected which were not made concrete? Do you think there is something that could be added to the lesson to insure that the standards you selected are developed while teaching the lesson?
• What would you add to this lesson to showcase that you know and can apply you state standards for instructional technology? Re-write this lesson, adding the use of instructional technology for both the teacher and the student where appropriate.

Title: Are All Starches the Same? Starch Explorations

Grade Levels: 5-8

Science Concepts to be learned

Main Concept to be invented: Each type of vegetable has a unique starch structure.

Secondary concepts important to expansion: Starch grain, hilum, slide preparation, microscope use

National Science Content Standard – from Life Science – Structure and Function in Living Systems Concepts 5-8:

Specialized cells perform specialized functions in multicellular organisms.

Disease represents a breakdown in structures or functions of an organism. Some diseases are the result of intrinsic failures of the system. Others are the result of infection by other organisms.

Learning Objectives:

Go to you state department of education website to find the learning outcomes that align themselves with this lesson. At all times you should address any outcome statements which address science as inquiry, the history and nature of science, science in personal and social perspectives, and science and technology. You should also identify an outcome statement which comes from your state's Life Science standards. List those in this section of the lesson.

Does your state have technology standards for students? These are not to be confused with the New Dimension of Science and Technology. Technology standards set the expectation for teachers to integrate educational technology tools into the curriculum. Read over the rest of the lesson below. Given the activities your students will be doing, add some activities or enhance the given activities to include the use of educational technology tools to this lesson. Review your state technology standards and list those that will now be addressed by your new additions to this lesson here. Be sure to label them Technology Standards.

Science Materials Needed:

For exploration activities:

For each group of 2-3 students provide:

• Microscope
• 5 slides
• 1 scalpel
• Cover slips
• Tapioca
• Picture of plant
• Background on the food source
• Rice grains which were soaked in water for at least 4 hours
  • Background on Rice
• Kidney Beans
  • Background info
  • Starch grains from bean embryo
• Corn kernels
  • Background on corn
• Corn Starch in polarized light
• Corn Starch
• Potatoes
• Background and cell view
• Close up slide l
• Black line picture of starch grains
• Electron microscope image
• Potato starch in polarized light

Classroom Management/Teaching Strategies

How will you organize the students?

For exploration and expansion activities: In teams of 2-3 per microscope

What are the safety issues you should address as the students participate in each of the activities?

Although the starches are edible, the students should be discouraged from tasting them. Caution should be used around electrical outlets for the electric microscopes. The bulb for the microscope will get hot. Safe techniques on the proper use of the scalpel should be reviewed and practiced with the students.

Activities to Support Concept Development

Exploration Phase (Student Activities): Microscopic Starch

Which process skills will be used? Observing, predicting, comparing, manipulating materials, recording data

Exploration - What will the students do?

The students will prepare slides of each of the given vegetables by using the scalpel to gently scrape a newly cut surface on the vegetable. A very small speck of each should be placed on each slide with a drop of water. A cover slip should be applied. The students should make predictions before observing the different starch grains. Since they are all starches, will all of the starch slides look alike? The students should record their prediction. The students should then observe each prepared slide under the microscope and draw their observations of the starch cell from each vegetable.

Explanation Phase (Teacher Activities):

What is the main idea? Each type of vegetable has a unique starch structure.

How will the main idea be constructed?

Ask the student teams to share their drawings for each slide. Ask them to share if their drawings confirmed or disproved their earlier prediction.

Some key questions to ask the students are:

• What did you observe as you looked at the potato slide?
• How were they different from the corn or rice?
• What did the bean and tapioca starch grains look like?
• Share with the students actual drawings of each type of starch grain. Ask the students to compare their drawings with the actual grains.
• Were you able to observe the detail shown in these pictures?
• Can you differentiate between the parts of the grain?
• Ask the students to complete this concluding statement: While potatoes, rice, and beans are all considered starches, they differ in their _______ (structure).

Additional information to develop the concept:

The students should find countless oval, ellipsoidal, or even triangular shaped, almost transparent bodies that look like miniature oyster shells when they observe the potato starch grains. Since the grains are not flat, it may help if the students slowly rotate the fine adjustment on the microscope back and forth to get all the parts in focus. Usually on the narrower end the students will find a tiny dark spot that is not in the center of the grain. This is called the hilum, the oldest part of the starch grain, around which the remainder of the shell has grown layer by layer until fully formed. If you focus up and down at this point, you will find concentric lines or rings called striations, which indicate the layers where the grain has grown larger and larger.

Corn starch is different from potato. The grains may have an irregular globular shape or a very distinct polygonal shape. The shape will vary depending on the part of the kernel the students take their samples from – the horny or the floury portion. Corn starch has a central hilum that is usually a point, but sometimes shows two, three, or four radiating clefts.

Rice starch grains are very small and many sided. They may be square, triangular, or pentagonal in shape. The hilum is not distinct, but in some grains a central portion appears brighter. This difference may be due to the drying of the grain. Ovoid or spherical shapes are usually due to a number of grains being compacted together.

Bean starch grains are usually ellipsoidal or kidney shaped. They have an irregular branching cleft running out from the center that appears black because of enclosed air.

Tapioca starch grains are usually circular or loaf shaped, depending on whether they sit on their flat surfaces or on their sides. The hilum is centrally located, usually coming to a point or small cleft. When students view the flattened surface, the hilum may appear triangular.

Expansion Phase (Student Activities):

Which process skills will be used? Observing, predicting, comparing, manipulating materials, hypothesizing, recording data, drawing conclusions

How will the idea be expanded?

• The students will brainstorm a list of other starch containing foods. The students should obtain these foods, prepare slides, predict which type of starch grain they think the food contains, and then check their prediction by viewing the slides. They should draw what they observe and compare it to the starch grains they observed during the exploration phase. Can they find starch grains similar to any of the previously identified grains? Are they finding starch grains which appear different in structure? What kind of starch do you think this food contains?
• The students may obtain several different kinds of beans. Pose a question: Will all beans contain the same kind of starch grains no matter the type of bean? Allow the students to design an experiment to answer that question.

In keeping with state and national standards for science education the New Dimensions of Science should be addressed in every lesson. I have added some examples of how you can address each dimension within this. Try your hand at creating some of your own questions to ask or discuss with your students that will address the following areas:

Science in Personal and Social Perspectives

• Do you think the differences in the starch grain will affect your ability to digest that starch? Why or why not?
• Are there any other kinds of plants that contain starch grains that humans do not eat? What are these? Why do you think we do not eat them? Do an internet search or survey local farmers and/or ranchers to determine which starch containing foods they use for their animals but do not use for human consumption.
• Why are starches important in a person’s diet? How would our diet be affected if some of the starch containing vegetables were threatened by disease?

Science and Technology

• Compare farming practices during the “Dust Bowl” days to today’s agricultural practices. How have our practices changed so that today in the United States we’re able to send starch containing vegetables to underdeveloped countries? What kinds of conditions are necessary to grow starch-containing foods? Can modern technology do anything to help these underdeveloped nations grow starches in their own countries?
• What kinds of products have modern industries created that make use of starches? How have these helped humans? How have these created problems for humans?

Science as Inquiry

• Are all starch grains, no matter the plant they come from, the same? Will starch grains from many different varieties of potato look the same? Why or why not? What could you do to find the answer to this question?
• What is the name of the oldest part of the starch grain? Does finding this structure under the microscope help in identifying the type of plant the starch grain came from?

History and Nature of Science

• Why do you think a person responsible for creating frozen dinners should understand that different vegetables have different starch structures?
• What kinds of jobs entail making careful observations and accurately recording what was observed?

Evaluation Phase

These may be re-stated as the lessons objectives – what do you expect the student to know and be able to do by the time they have completed all phases of the lesson?

Cognitive: involve intellectual activities such as memorizing, interpreting, applying, problem solving, reasoning, analyzing and critical thinking.

• Why can some starch grains be digested by humans while others can not?

Performance: engages students in activities that require them to apply their understanding of the concept in a new context.

• Prepare a slide of starch grains
• Accurately draw starch grains observed under a microscope
• Identify with 80% accuracy the various starch grains and their sources

References

Martin, Ralph E. Colleen M. Sexton and Teresa Franklin (2005). Teaching Science for ALL Children. Boston: Allyn and Bacon publishers.