Description:

Students will determine the mass, volume, and density of two mineral samples using measurement tools.

This task assesses students' abilities to determine and record precise measurements of mass and volume, apply mathematics, calculate density, and give logical, scientific explanations.

This task is designed to take students approximately 20 minutes to complete.

Overall Task Content Area:

Earth Science

Specific Knowledge Areas:

Properties and changes of properties in matter

Performance Expectations:

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

National Science Education Standards:

8 B PS 1: Properties and changes of properties in 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.

8 A SI 1: Abilities necessary to do scientific inquiry: Grades 5-8
1.3 Use appropriate tools and techniques to gather, analyze, and interpret data. The use of tools and techniques, including mathematics, will be guided by the question asked and the investigations students design. The use of computers for the collection, summary, and display of evidence is part of this standard. Students should be able to access, gather, store, retrieve, and organize data, using hardware and software designed for these purposes.

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.

1.5 Think critically and logically to make the relationships between evidence and explanations. Thinking critically about evidence includes deciding what evidence should be used and accounting for anomalous data. Specifically, students should be able to review data from a simple experiment, summarize the data, and form a logical argument about the cause-and-effect relationships in the experiment. Students should begin to state some explanations in terms of the relationship between two or more variables.

(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:

MEAS2: Apply appropriate techniques, tools, and formulas to determine measurements:
Grades 6-8 k. select and apply techniques and tools to accurately find length, area, volume, and angle measures to appropriate levels of precision
Grades 6-8 o. solve simple problems involving rates and derived measurements for such attributes as velocity and density

NO1: Understand numbers, ways of representing numbers, relationships among numbers, and number systems:
Grades 6-8 q. understand and use ratios and proportions to represent quantitative relationships

NO2: Understand meanings of operations and how they relate to one another:
Grades 6-8 h. understand the meaning and effects of arithmetic operations with fractions, decimals, and integers

PS3: Apply and adapt a variety of appropriate strategies to solve problems:
Grades 6-8

COM1: Organize and consolidate their mathematical thinking through communication:
Grades 6-8

CON1: Recognize and use connections among mathematical ideas:
Grades 6-8

REP1: Create and use representations to organize, record, and communicate mathematical ideas:
Grades 6-8

General Instructions to the Teacher:

This task is designed to take approximately 20 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 "Density of Minerals":

The teacher will need:

• extra paper towels

At each station students should have:

• metric balance
• graduated cylinder (ml)
• overflow cup
• beaker and water
• mineral samples A & B
• calculator
• paper towels

Preparation:

A. Selection of mineral samples:

The samples must:

• fit the size of the overflow cups
• not be soluble
• be those that students are familiar with

B. Marking samples:

• Use white paint and a fine tip permanent marker
• Mark the samples A1; B1; A2; B2; etc.

C. Measure mass and volume of samples and record data for use in scoring student work.

Safety:

• If graduated cylinders are glass, place a small amount of modeling clay at the bottom of the cylinder to prevent breakage should a mineral sample be dropped.
• 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:

If small specimens of minerals are available and overflow cups are not, minerals may be lowered with a string into the graduated cylinders to get a volume reading.