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Contents

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

Introduction

The Changes 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.

The Changes unit invites children to explore how materials change when they are mixed and to recognize that there are different types of changes. Students investigate physical changes by combining materials to create heterogeneous and homogeneous mixtures. In exploring chemical changes, they produce new substances, such as fizzing liquids and rust. The investigations allow students to learn about different indicators of change. Students also begin to understand that changes can happen slowly or quickly and that they can occur naturally, or as the result of human intervention. These investigations enable second-graders to appreciate that changes are occurring all around them and to develop an interest in further exploring these phenomena.

Contents

Lesson 1: Thinking About How Things Change

Lesson 2: Freezing and Melting

Lesson 3: Where Did the Water Go?

Lesson 4: Mixing and Separating Solids

Lesson 5: Mixing Solids and Liquids

Lesson 6: Separating Solid and Liquid Mixtures

Lesson 7: A Dissolving Race: Two Forms of Sugar

Lesson 8: A Dissolving Race: Warm and Cold Water

Lesson 9: Changing Salt Water to Crystals

Lesson 10: Separating Mixtures of Color

Lesson 11: Separating a Mystery Mixture

Lesson 12: Bubbles and Fizz: Observing a Chemical Reaction

Lesson 13: Gas in a Bag

Lesson 14: Looking at Rust

Lesson 15: Writing Our Recipes for Change

Lesson 16: Presenting Our Recipe for Change

Objectives

Students are expected to:

• observe and describe changes.
• classify changes as physical or chemical.
• communicate results through writing and drawing.
• predict, observe, classify, and record results.
• separate mixtures through sieving, filtering, and evaporation.
• work cooperatively.
• develop an awareness that changes occur in the world around us.
• develop interest in and enthusiasm for investigating physical and chemical changes.
• become comfortable using a variety of materials.
• develop an appreciation for the importance of organizing information on charts, on record sheets and in science journals.

Concepts

• Changes occur all the time in the world around us.
• Changes can occur naturally or because of human intervention.
• Some changes happen quickly and others take place over a period of time depending on the materials that are used.
• Mixing materials produces a physical change, a chemical change, or a combination of the two.
• Physical changes and chemical changes each have unique characteristics.
• Chemical changes produce new materials with new properties; the original materials no longer exist.
• In a physical change, the physical properties of a material are altered, but the material remains the same kind of matter.
• Heterogeneous and homogeneous mixtures retain the properties of the materials from which they were made.
• A mixture is a combination of two or more pure materials that can be separated into their original components.
• Materials have observable physical properties such as color, size, shape, odor, texture, and state (solid, liquid, gas).
• Heterogeneous and homogeneous mixtures can be separated into their original materials through sieving, filtering, or evaporation.
• The components of a heterogeneous mixture are easily recognized, while the individual parts of a homogeneous mixture are more difficult to recognize.
• The rate of dissolving can be affected by stirring, the temperature of the solvent, the amount of solute placed in the solvent, and the size of the solute particles.

District Standards

The Changes 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. 2.3.b, 2.3.c.)

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 Changes kit, assessment is an ongoing, integral part of instruction. Because assessment emerges naturally from the activities in the lessons, students are assessed in the same manner in which they are taught. They may perform experiments, record their observations, or make oral presentations. Such assessments permit the examination of processes as well as of products, emphasizing what students know and can do. 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 9-12 in the teacher's guide. Appendix A contains additional final assessments and a student self-assessment.

This web page is maintained by Leanne Graves.