Description:

The task assesses students’ ability to make simple observations, design simple experiments, utilize indicators, and make generalized inferences from their observations.

This task is designed to take students approximately 10-15 minutes to complete.

Overall Task Content Area:

Physical Science

Specific Knowledge Areas:

Properties of matter

Performance Expectations:

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

National Science Education Standards:

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.

8 B PS 1: Properties of matter: Grades 5-8
1.1 A substance has characteristic properties, such as density, a boiling point, and solubility, all of which are independent of the amount of the sample. A mixture of substances often can be separated into the original substances using one or more of the characteristic properties.

(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:

General Instructions to the Teacher:

This task is designed to take students approximately 10-15 minutes to complete.>

Students will be working individually during this exercise.

Students should be ready to work as soon as the period begins. 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 for "Sugar and Starch Testing 2":

• Dropper bottles labeled A, B, and C
• Dropper bottle with iodine
• Glucose test strip/stick
• Laminated test card or transparency test card
• waste container (cup or small pail)
• wax paper
• paper towels
• safety goggles

Advance Preparation:

• Glucose and starch solutions can be obtained from a science supply company.
• Put glucose solutions in bottles A and B.
• Put starch solution in bottle C.
• Glucose test strip/sticks can be obtained from a science supply company or a drug store.
• Keep the glucose strips away from the iodine solution. The fumes will turn the strips black or green.
• Be sure to test glucose and starch solutions before using them with the students.
• The glucose and starch solutions can be diluted two or three times. They will be more effective than full strength.
• Wax paper should be cut to fit over the test card. This will keep the test card from becoming contaminated. If using transparency test card be sure to discard when each student is finished.

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.
• Students must wear safety goggles when working with iodine solution.
• Check MSDS (Materials Safety Data Sheet) for further laboratory precautions.

Extensions/modifications:

• Glucose test tape is no longer manufactured. You may use glucose test strips/sticks found at a drugstore. These are quite expensive so a teacher demo may be more appropriate.
• To do a Teacher Demo you might use an overhead projector with a transparency sheet marked with three circles marked "A", "B", and "C". The students could then check the color on the glucose strips as well as see the iodine change when the materials were added.
• There is also a task entitled, "Starch and Sugar Testing 1", with a different degree of structure.