8-12 Lesson 6

Sunrise...Sunset - Bilingual Telemation Unit

8-12 Lesson 6:
Crops and Seasons

Concept:

Seasonal changes in temperature and light affect crop growth and productivity. These changing conditions determine the best time to plant crops.

The Scientific Investigation:

How do changing seasonal conditions of temperature and the amount of light affect crop productivity?

Purpose:

Students will grow four different crops to determine how seasonal temperature and light changes affect growth. Students will calculate the altitude angle of the sun.

Materials:

Horticulture area with good, well-draining soil

Hose and gardening tools

Radish, cilantro, corn, and bean seeds

Thermometer

3.3 meter stick

Meter sticks for measuring shadow and plants

Daily sunrise/sunset info (from weather section of newspaper)

Student Worksheet (Spanish)

Procedure:

If a horticulture area is not available, you may wish to measure the altitude angle of the sun and compare soil temperatures to the amount and angle of sunlight. When doing farming with students, divide the garden into rows. Groups of students can be responsible for different rows.

Make sure the soil is well prepared before the planting day. Observations once a week should be more than sufficient. You may wish to repeat this experiment once during the cool months and again during the warmer months, preferably for a total of four times a year so that you can compare their performance in each season.

You may wish to change the crops. The four chosen are very easy to grow. Each has different temperature requirements to reach harvest. Corn needs the hottest weather. Cilantro and radishes will grow in cooler weather. If you wish to be historically accurate to the crops grown in MesoAmerica, you may want to eliminate these two and choose instead squash and tomatoes (however these are both summer crops). Tomatoes are difficult to grow from seed. This is a good opportunity to discuss New World food contributions.

Set up the stick for altitude angle permanently in a location not impeded by shade, preferably in the garden itself. Teach students how to calculate the angle in the classroom. They can use a scientific calculator or a tangent table. If you do not want to mention trigonometry, they can compare shadow lengths. Note: Tan (angle) = height of stick/length of shadow.

Assessment:

Scientists work in a very methodical fashion. Maintaining accurate records of observations and measurements is a key component in this systematic method. Every student should keep accurate chronological record, possibly in a scientific investigations journal or science lab book, of everything which they do in the investigation. These notes should be placed within the student's portfolio for assessment purposes.

It is very important that a student understand that different types of living organisms have different requirements from the natural environment in which they thrive. A student's notes in this investigation should reflect the increase in the student's knowledge of what a living organism requires for life. The student should include documentation of their growth in these note taking skills in their portfolio.

Assessment of the quality of the student's work should respond to a rubric. This assessment tool describes how the level of involvement and completeness of a student's work will be related to the evaluation they will receive for the portfolio. Refer to a sample of a rubric included at the conclusion of these lessons.

Conclusion:

How do light and temperature affect the growth of the plants in this investigation? Can plants tell time? How do plants know when there are long enough days for them to successfully reproduce? Why don't "winter" crops, which seem to thrive in short days, grow successfully in the summer months as well? What winter crops are grown on farms in your area? What summer crops thrive where you live?

Extensions:

Mathematics:

Natural phenomena, like growth, are very complicated indeed. But we often reduce these exceedingly complex activities to a series of measures of changes in length and mass. The mathematical notion of defining variables is often not appreciated for how significant a step this is in the use of mathematics in science. Why is the measure of the change in length of some part of a living organism considered to be an important indicator of growth? What does change in mass have to do with this complex process? As growth certainly involves development, why are we so quick to separate "development" from "growth"? The mathematics which we are able to currently use efficiently can not deal with the complex nature of the huge number of variables in this process. Thus we report that "it's" not able to be "quantified." Try to get your students to understand how our understanding of mathematics has influenced our understanding of nature.

Language Arts:

Communication between the participants in this investigation who reside in different schools and are far removed from one another will be through the transmission of text files using the medium of telecommuciations. Students should prepare their messages in a word processor, making corrections as necessary to clarify what they wish to send to others who are working with them on the project. The word processing file should then be saved as an ASCII file, up-loaded, and sent within the time frame of the project's schedule.

Language Development Strategies:

Communication via telecomputing requires the use of written statements. One important advantage of using computers to communicate with one another is that "what you read is all that you know." Students will be encouraged to ask people to clarify their written messages when they are not clearly communicating ideas to the other party. Through these feed-back techniques, students will learn how to more effectively and clearly communicate with people with whom you are not able to explain yourself.

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