Description:

Students will investigate how different variables affect seed growth. Variables include type of seed, medium (paper towels, various types of soil), amount of water, amount of light, temperature.

The task assesses students' understanding of scientific inquiry including the following skills: observation, data collection, measurement, graphing, scientific questions.

This task is designed to take students approximately 10 hours over about 2 weeks.

Overall Task Content Area:

Life Science

Specific Knowledge Areas:

Describe basic needs of living things

Performance Expectations:

• conducting investigations
• using equipment
• gathering, organizing, and representing data
• formulating conclusions from investigational data

National Science Education Standards:

8 A SI 1: Abilities necessary to do scientific inquiry: Grades 5-8

1.1 Identify questions that can be answered through scientific investigations. Students should develop the ability to refine and refocus broad and ill-defined questions. An important aspect of this ability consists of students' ability to clarify questions and inquiries and direct them toward objects and phenomena that can be described, explained, or predicted by scientific investigations. Students should develop the ability to identify their questions with scientific ideas, concepts, and quantitative relationships that guide investigation.

1.2 Design and conduct a scientific investigation. Students should develop general abilities, such as systematic observation, making accurate measurements, and identifying and controlling variables. They should also develop the ability to clarify their ideas that are influencing and guiding the inquiry, and to understand how those ideas compare with current scientific knowledge. Students can learn to formulate questions, design investigations, execute investigations, interpret data, use evidence to generate explanations, propose alternative explanations, and critique explanations and procedures.

1.4 Develop descriptions, explanations, predictions, and models using evidence. Students should base their explanation on what they observed, and as they develop cognitive skills, they should be able to differentiate explanation from description — providing causes for effects and establishing relationships based on evidence and logical argument. This standards requires a subject knowledge base so the students can effectively conduct investigations, because developing explanations establishes connections between the content of science and the contexts within which students develop new knowledge.

1.7 Communicate scientific procedures and explanations. With practice, students should become competent at communicating experimental methods, following instructions, describing observations, summarizing the results of other groups, and telling other students about investigations and explanations.

8 C LS 1: Structure and function in living systems

1.1 Living systems at all levels of organization demonstrate the complimentary nature of structure and function. Important levels of organization for structure and function include cells, organs, tissues, organ systems, whole organisms, and ecosystems.

(Use the "hot" link on the PALS home page to check the full text of related National Science Education Standards, if desired.)

National Council of Teachers of Mathematics:

Background: All seeds consist of two parts, the embryo and the seed coat. The seed coat protects the developing plant and embryo. Cotyledons store food. They are They are the leaves that are attached to the embryo. When the seed begins to grow, one part of the embryo becomes the root and the rest of it becomes the upper stem and leaves.

Procedure:

1. Remove 1 seed each day to dissect, examine with and w/o hand lens, sketch and diagram.
2. Observe and describe the wet seeds. Find the spot where the seed was attached to the pod. This small hole in the coat allows water to enter the seed.
3. Remove the seed coat and split the seed into parts. While examining these parts, identify the basic parts of the seed. Can you see the shape of the future leaves?
4. Discuss how the wet and dry seeds are different from each other.

Background: Seeds will start to grow when conditions are right to support the needs of the growing plants. Seeds need water, air, and proper temperature for growth. Water makes the seed swell and it softens the coat. When this happens, the embryo (tiny plant) begins to grow. In order to germinate, seeds need warm temperature. The embryo grows into a young plant which needs food, air, soil, water, light, and space to grow.

Procedure:

1. Distribute lima beans to each group of 3-4 students.
2. Tape 2 paper towels inside a zip-lock bag, which the students label so that they know which is their group's bag.
3. Saturate the paper towels with water. Measure the amount of water (ml, tbs) it takes to saturate the paper towels.
4. Place the seed on top of the dampened paper towel, and seal the zip-lock bag.
5. Tape the zip-lock baggies to the classroom window or on a bulletin board.
6. Keep a daily observation log. In this log the students can make observations and measurements, draw pictures, record data, and plot the plant's growth. The students will observe that the seeds have roots that grow toward the floor and stems that grow toward the sky. They can measure the stem's growth, as well as the root's growth. They can then graph the results.
7. Discuss with the class: How did we provide for the needs of the seed's growth? This could lead to a discussion on how the plant's needs are different than the seed's needs. Be prepared to discuss these differences.
8. Discuss the variables that were present, which affect the seed's germination or growth:

• type of seed
• medium (paper towels, soil)
• amount of water
• amount of light
• temperature

1. Discuss the variables that were constant in this particular investigation.

Safety:

• Be careful.
• Teachers and students should always exercise appropriate safety precautions and utilize appropriate laboratory safety procedures and equipment when working on science performance tasks.

Extensions/modifications:

• Optional: The student will observe lima beans that have been soaked in water overnight and identify the major parts of the seed.