Unit Plan 4 (Grade 5 Science): Mixtures & Solutions

Focus: Plan and carry out investigations to describe how different materials behave when mixed (forming mixtures and solutions) and use those behaviors as properties to help identify materials.

Grade Level: 5

Subject Area: Science (Physical Science • Matter & Properties)

Total Unit Duration: 5 sessions (one week), 50–60 minutes per session

I. Introduction

In this unit, students explore how substances behave when they are combined, comparing simple mixtures (like sand and iron filings) and solutions (like saltwater). Through hands-on investigations, they observe whether materials dissolve, settle, float, separate with filters or magnets, or leave residue after evaporation. Students learn that these “mixing behaviors” are properties that can be used to identify materials and decide how to separate components in real-world contexts (food, water treatment, recycling).

Essential Questions

• How can we tell the difference between a mixture and a solution by observing what happens when substances are mixed?
• How do behaviors like dissolving, settling, floating, and separating help us identify materials?
• Why do scientists and engineers plan systematic investigations instead of just guessing when they mix substances?
• How do people use knowledge of mixtures and solutions to solve problems in everyday life (like water cleaning or cooking)?

II. Objectives and Standards

Learning Objectives — Students will be able to:

1. Describe and give examples of mixtures and solutions, noting how the components behave when mixed.
2. Plan and conduct simple investigations to observe how different solids and liquids behave when mixed with water (e.g., dissolve, float, sink, settle, form layers).
3. Test and record how mixtures can be separated using tools such as filters, magnets, sieves, and evaporation, and connect these behaviors to material properties.
4. Use organized data tables to compare how different substances behave when mixed and separated.
5. Use patterns in mixing/separation data to identify unknown materials by their behaviors in mixtures and solutions.

Standards Alignment — 5th Grade (NGSS-Aligned)

• 5-PS1-3 — Make observations and measurements to identify materials based on their properties.
  • Example: Students compare how unknown white powders behave when mixed with water (dissolve or not), stirred, filtered, and evaporated, and use the resulting data to identify which powder is which.

Success Criteria — Student Language

• I can explain what a mixture is and what a solution is, and give examples of each.
• I can observe and record what happens when different substances are mixed with water (do they dissolve, float, sink, or form layers?).
• I can describe ways to separate mixtures (like using filters, magnets, sieves, and evaporation) and what that tells me about the materials.
• I can use a data table to compare how substances behave when mixed and separated.
• I can use my observations and measurements to identify an unknown material based on how it behaves in a mixture or solution.