Description:

Students will design and conduct an experiment to test their ideas about how to speed up or slow down the rate of an enzyme-catalyzed reaction. Students will have access to an array of physical and chemical factors that might influence enzyme activity. They are expected to predict how one of the factors might affect the reaction rate and test it in a high quality experiment.

The task assesses students' understanding of effects of wind and running water on Earth's materials and scientific inquiry including the following skills: observation, background research, scientific procedures (including investigation design, measurement techniques, and error analysis), data collection, data display, scientific questions, formulating an hypothesis.

This task is designed to take students approximately 2 hours

Overall Task Content Area:

Earth Science

Specific Knowledge Areas:

Earth surface changes over time

Properties and uses of Earth materials

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

1.2 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.

4 D ESS 1: Properties of earth materials: Grades K-4

1.2 Soils have properties of color and texture, capacity to retain water, and ability to support the growth of many kinds of plants, including those in our food supply.

8 D ESS 1: Structure of the earth system: Grades 5-8

1.5 Soil consists of weathered rocks and decomposed organic material from dead plants, animals, and bacteria. Soils are often found in layers, with each having a different chemical composition and texture.

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

General Instructions to the Teacher:

This task is designed to take students approximately 2 hours. .

Students should be ready to work as soon as periods begin. A central supply area, if needed, should be easily accessible. All supplies should be clearly labeled.

Materials for " Water-holding Capacity of Earth Materials ":

The student will need:

• balance
• funnels
• clock/timer
• paper towels
• dry sand
• water (approx. 800ml.)
• funnel supports (ring stands or tripod)
• wax marking pens
• paper cups
• dry sphagnum moss
• graduated cylinder
• 250ml beakers
• spoons
• dry potting soil
• pieces of filter paper-coffee or lab-(18.5 cm in diameter)
• other Earth materials

Advance Preparation:

• A stream in your area has a flooding problem, while a stream on the other side of the mountain doesn't. The rainfall is the same.
• In Northeastern Oregon, irrigation is used extensively. The water requirement of the plants is such that water is required frequently. It has been noted that within days of being irrigated, the soil is dry and needs more water.
• On one hillside there is an erosion problem.

Students could bring in soil samples from their households to test for water holding capacity.

Student engagement activity: After the first rain of the season (fall), we don't see a lot of flooding in the area. After several rainy days, we may see many runoff or flooding problems. The retention of the water by different materials affect soil erosion.

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:

• Helpful resources: National Science Teacher Association: Science Educator's Guide to Assessment, 1998, p.170