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ME402: Growth of Yeast
Administration Procedures
Grade 5-8 Performance Task
Contributed by: Council of Chief State School Officers (CCSSO)

Description:

Students investigate the growth of yeast in a sugar solution. They verify the presence of carbon dioxide using bromothymol blue. Students are then asked to describe the difference between the contents of the test tubes used and to explain the purpose for this particular difference. Finally, students are shown a graph of yeast cell population v. time and asked to describe two conditions that could prevent the number of living yeast cells from increasing with time beyond a certain point.

This task is designed to take students approximately 40-50 minutes to completely.

Overall Task Content Area:

Life Science

Specific Knowledge Areas:

Populations and ecosystems

Performance Expectations:

  • conducting investigations
  • using equipment
  • gathering, organizing, and representing data
  • formulating conclusions from investigational data
  • applying scientific principles to develop explanations and solve new problems

National Science Education Standards:

8 C LS 1:  Structure and function in living systems:  Grades 5-8
4.4 The number of organisms an ecosystem can support depends on the resources available and abiotic factors, such as quantity of light and water, range of temperatures, and soil composition. Given adequate biotic and abiotic resources and no disease or predators, populations (including humans) increase at rapid rates. Lack of resources and other factors, such as predation and climate, limit the growth of populations in specific niches in the ecosystem.

8 A SI 1:  Abilities of scientific inquiry:  Grades 5-8
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.

(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:

DAP3: Develop and evaluate inferences and predictions that are based on data :
Grades 6-8 c. use observations about differences between two or more samples to make conjectures about the populations from which the samples were taken
Grades 6-8 e. use conjectures to formulate new questions and plan new studies to answer them

MEAS1: Understand measurable attributes of objects and the units, systems, and processes of measurement :
Grades 6-8 j. understand both metric and customary systems of measurement

AL1: Understand patterns, relations and functions:
Grades 6-8 f. represent, analyze, and generalize a variety of patterns with tables, graphs, words, and, when possible, symbolic rules

AL4: Analyze change in various contexts:
Grades 6-8 e. use graphs to analyze the nature of changes in quantities in linear relationships

PS2: Solve problems that arise in mathematics and in other contexts:
Grades 6-8

RP2: Make and investigate mathematical conjectures:
Grades 6-8

CON3: Recognize and apply mathematics in contexts outside of mathematics:
Grades 6-8

General Teacher Instructions:

This task is designed to take students approximately 40-50 minutes to complete.

Students will be working in groups of 4-6 for the experiment/activity part of this exercise. Each student must record the information in his or her own booklet (test papers). Allow from 20 minutes to complete the group work. If students are still working together 20 minutes after the testing begins, instruct them to cease their group work and begin individual work. At this point, they may no longer talk. Whether or not they are just beginning their individual work, remind students that they now have about 25 minutes to complete the individual activity.

Students should be ready to work as soon as the period begins. Group assignments should be made in advance. The materials should be set out at each lab station, if possible. A central supply area, if needed, should be easily accessible. All supplies should be clearly labeled.

Materials in Kits:

At this station students should have:

  • 5 20x150 mm test tubes
  • 1 glass stirring rod
  • 1 tsp dry yeast
  • 1 tsp sugar
  • Three 7-inch (long) balloons that are round when inflated
  • One 25 ml graduated cylinder
  • bromothymol blue indicator, 0.004% aqueous solution (BTB)
  • two 1/4 teaspoon measuring spoons
  • 1 plastic cup, 500 ml
  • one 0-100oC thermometer
  • one test tube rack
  • one bottle distilled water
  • hot water
  • safety glasses
  • aprons
  • 1 straw
  • stopwatch or clock
  • paper towels
  • markers

Advance Preparation:

Group assignments, if used, should be made in advance.

Special Teacher Instruction

Students should see that foam and bubbles do not get into the balloons. When the foam gets close to the top of the tube, the balloons should be pinched off.

ME402

General Teacher Instruction:

Students will be working in groups of 4 - 6 for the experiment/activity part of this exercise. The following suggestions are offered to facilitate administration of the exercise.
  • Students need to be ready to work as soon as the period begins.

  • Group assignments should be made in advance.

  • The materials should be set out at each lab station, if possible.

  • A central supply area, if needed, should be easily accessible.

  • The supply area should have any supplies from the kit that were prepared by the teacher as well as all of the school-supplied materials necessary for the experiment.

  • All the supplies should be clearly labeled.

Materials in Kits:

  • 5 20 x 150 mm test tubes
  • 1 glass stirring rod
  • 1 tsp dry yeast
  • 1 tsp sugar
  • Three 7-inch (long) balloons that are round when inflated. (One balloon is an extra.)
  • One 25 ml graduated cylinder
  • Bromothymol Blue indicator, 0.004% aqueous solution (BTB)
  • Two 1/4-teaspoon measuring spoons
  • 1 plastic cup, 500 ml
  • One 0-100oC thermometer
  • One test tube rack
  • One bottle distilled water

Materials Supplied by School or Students:

  • hot water
  • safety glasses
  • aprons
  • 1 straw
  • stopwatch or clock
  • paper towels
  • markers

Special Teacher Instructions:

Students should see that foam and bubbles do not get into the balloons. When the foam gets close to the top of the tube, the balloons should be pinched off.

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.

 

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