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Contents

• Introduction
• Contents
• Objectives
• Concepts
• District Standards
• Assessment

Introduction

The Chemical Tests unit is a Science and Technology for Children (STC) kit developed by the National Science Resources Center at the Smithsonian Institute in Washington D.C.

Throughout the unit, students explore the properties of five common "mystery" powders. They mix water with the powders and conduct various experiments involving solubility, filtration, evaporation, and crystallization. Students also test the powders with heat, iodine, and red cabbage juice and describe the changes that occur. After establishing the identity of the powders, students apply their skills to identify the components of combinations of powders.

Contents

Lesson 1: Thinking about Chemicals

Lesson 2: Investigating Unknown Solids

Lesson 3: Exploring the Five Unknown Solids

Lesson 4: Testing Unknown Solids with Water

Lesson 5: Exploring Water Mixtures

Lesson 6: Discovering Crystals

Lesson 7: Testing Unknown Solids with Vinegar

Lesson 8: Testing Unknown Solids with Iodine

Lesson 9: Testing Unknown Solids with Red Cabbage Juice

Lesson 10: Testing Unknown Solids with Heat

Lesson 11: Reviewing the Evidence

Lesson 12: Identifying the Unknown Solids

Lesson 13: Identifying the "Mystery Bag Chemical"

Lesson 14: Testing Mixtures of Two Unknown Solids

Lesson 15: Testing Household Liquids with Red Cabbage Juice

Lesson 16: Using the Known Solids to Identify Unknown Liquids

Objectives

Students are expected to:

• observe and describe properties of materials.
• learn to perform different physical and chemical tests.
• predict, observe, describe and record results of tests.
• analyze and draw conclusions from the results of tests.
• compare and contrast test results to define the properties of household chemicals so they can be identified.
• support conclusions with reasons based on experiences.
• communicate results reflecting on experiences through writing and discussion.
• apply previously learned knowledge and skills to new situations to solve a problem.
• read to enhance understanding of chemistry concepts.
• develop proper lab techniques to ensure safety and avoid contamination.
• develop interest in and enthusiasm toward exploring and investigating properties of chemicals.
• recognize the importance of guidelines for experimentation.
• develop an awareness of the importance of chemicals in our lives.
• develop an appreciation for the safe handling of chemicals.

Concepts

• Common household chemicals have different physical and chemical properties.
• Chemicals undergo changes in form, color, or texture when they are mixed together, separated, or heated.
• Some chemicals can be identified by their interaction with water, vinegar, iodine, red cabbage juice and heat.
• Different types of mixtures, such as solutions or suspensions, are created when solids are combined with water.
• Evaporation and filtration are methods for separating mixtures of solids and liquids.
• Some chemicals can be classified as acids, bases, or neutral substances by their reactions with red cabbage juice.

District Standards

The Chemical Tests kit meets the following District Standards:

Standard 1. Students understand the process of scientific investigation and design, conduct, communicate about, and evaluate such investigations. (1.a., 1.b., 1.c., 1.d.)

Standard 2. Physical Science: Students know and understand common properties, forms, and changes in matter and energy. (2.1.a., 2.1.b., 2.1.c., 2.2.a., 2.2.b., 2.3.a.)

Standard 4. Earth and Space Science: Students know and understand the processes and interactions of Earth's systems and the structure and dynamics of Earth and other objects in space. (4.3.b.)

Standard 6. Students understand that science involves a particular way of knowing and understand common connections among scientific disciplines. (6.a., 6.b.)

Assessment

In the Chemical Tests kit, assessment is an ongoing, integral part of instruction. Strategies fall into three categories: matched pre- and post-unit assessments, embedded assessments, and final assessments. The pre/post-unit assessment questions provide two sets of comparable data to indicate student growth in knowledge and skills. Embedded assessments are woven into the unit and provide an ongoing profile of student progress and thinking. Specific guidelines for a variety of assessments are found at the end of several lessons. A detailed assessment chart may be found on pages 10-11 in the teacher's guide. Appendix A contains additional final assessments and a student self-assessment.

This web page is maintained by Leanne Graves.