Science · 1st Grade · Properties of Materials · Weeks 19-27

Changing Materials: Mixing

Students explore how mixing different materials can create new substances with new properties.

• Common Core State Standards
• 2-PS1-2

About This Topic

When two or more materials are combined, something new may form. Standard 2-PS1-2 asks students to analyze data from testing materials to determine which materials have the properties best suited for an intended purpose, and the mixing extension asks them to observe and describe what happens when materials are combined, including whether a new substance with new properties has formed. At the first-grade level, this means investigating simple mixes like salt and water, flour and water, or baking soda and vinegar, and comparing the properties of the starting materials with the properties of the result.

Some mixes are easy to separate back into their original components. Salt dissolved in water can be recovered by evaporation. Others produce an entirely new substance, like the gas and foam produced when baking soda and vinegar react. Those changes produce materials with properties neither starting material had, an early, concrete introduction to the idea of chemical change.

Active learning is essential for this topic because mixing is an inherently hands-on experience. The surprise of a baking soda-vinegar reaction, the unexpected texture of cornstarch and water, or the clarity of salt dissolving creates genuine scientific curiosity that motivates closer observation and better questioning. When students mix materials themselves and then describe what they find, they generate real data from real experience.

Key Questions

1. Analyze what happens when two different materials are mixed together.
2. Differentiate between a mixture and a new substance formed by mixing.
3. Design an experiment to create a new material by mixing.

Learning Objectives

• Compare the properties of original materials with the properties of a mixture.
• Identify whether a new substance has formed after mixing two or more materials.
• Design a simple experiment to test the effect of mixing specific materials.
• Explain the difference between a mixture and a new substance formed by mixing.

Before You Start

Identifying Properties of Materials

Why: Students need to be able to observe and describe basic properties like color, texture, and state (solid/liquid) before they can compare them to new properties after mixing.

Observing Changes in Materials

Why: Students should have prior experience observing simple changes, such as melting ice or tearing paper, to build foundational observation skills for this topic.

Key Vocabulary

mixture	A combination of two or more substances that are physically blended but not chemically bonded. The original substances keep their own properties.
new substance	A material formed when substances are mixed and chemically change, resulting in new properties that the original substances did not have.
properties	The characteristics of a material, such as color, texture, hardness, or how it behaves when mixed with other things.
dissolve	To mix one substance into another so that it disappears and forms a solution, like sugar dissolving in water.

Watch Out for These Misconceptions

Common Misconception

Mixing always creates something completely new and unrecoverable.

What to Teach Instead

Students often assume that once materials are mixed, they are permanently changed. Demonstrating the salt-water evaporation experiment over several days shows that some mixtures can be separated. This helps students distinguish between physical mixtures, which can often be separated, and chemical changes, where recovery is not possible.

Common Misconception

The two mixed materials both disappear into the new substance.

What to Teach Instead

Students sometimes think the original materials are destroyed when mixed. A simple example is mixing red and blue paint to get purple: the original colors are no longer visible, but the same amount of material is present. Connecting this to conservation of matter establishes that mixing does not create or destroy material but changes how it is combined.

Common Misconception

If you cannot see a change, nothing happened when the materials were mixed.

What to Teach Instead

Sugar dissolved in water seems to disappear, making students think it is gone. Tasting the water or evaporating it to reveal crystals corrects this. Not all changes in properties are visible to the naked eye, which introduces students to the idea that careful observation sometimes requires multiple senses or time to reveal the full result.

Active Learning Ideas

Inquiry Circle: Mix and Observe Lab

Small groups receive three mixing challenges: salt and water, flour and water, and baking soda and vinegar. For each mix, they record the properties of the starting materials, make the mix, and then record the properties of the result. They compare the three results and describe which mix produced something that seemed most different from either starting material.

40 min·Small Groups

Think-Pair-Share: Can We Get It Back?

After observing a salt-and-water mix, ask students whether they think they can get the salt back. Students pair to discuss how, then watch the teacher demonstrate placing some salt water in a shallow dish to allow evaporation over several days. At the follow-up session, students observe the remaining crystals and describe what they see.

20 min·Pairs

Gallery Walk: Before and After Mixing

Post paired photo cards showing 'before mixing' and 'after mixing' images for eight combinations: baking soda and vinegar, paint colors mixed, sand and gravel, flour and eggs, coffee grounds and water, sugar and water, clay colors mixed, and wood shavings and glue. Students categorize each pair as 'still separable' or 'formed something new' and note their observable evidence.

25 min·Individual

Simulation Game: The Oobleck Challenge

Each pair mixes 2 parts cornstarch and 1 part water to make oobleck. They observe its properties: does it flow like a liquid? Does it hold its shape like a solid? They test it by hitting it sharply, pressing slowly, and rolling it in their hands. Students describe what is puzzling about this mixture and compare its properties to both the cornstarch and the water separately.

30 min·Pairs

Real-World Connections

• Bakers mix ingredients like flour, sugar, eggs, and butter to create new batters and doughs with unique textures and flavors for cakes and breads.
• Chefs combine spices, oils, and vinegars to make salad dressings, where the different ingredients blend to create a new taste and consistency.
• Construction workers mix cement, sand, and water to form concrete, a strong new material used to build roads, bridges, and buildings.

Assessment Ideas

Exit Ticket

Provide students with two small cups, one with sand and one with water. Ask them to draw what happens when they mix them in a third cup. Then, ask: 'Did a new substance form? How do you know?'

Quick Check

Show students a prepared mixture, like salt dissolved in water, and the original salt and water. Ask: 'What did we mix? What do you observe now? Is this a mixture or a new substance? How can you tell?'

Discussion Prompt

Present a scenario: 'Imagine you mix baking soda and vinegar. You see fizzing and bubbles. What does this tell you about whether a new substance formed? How is this different from mixing sand and water?'

Frequently Asked Questions

What happens when you mix baking soda and vinegar?

Baking soda is a base and vinegar is an acid. When they combine, a chemical reaction produces carbon dioxide gas, which is the bubbling you see. The new substances produced include water and a salt called sodium acetate. The properties of the result are very different from either starting material, and the change cannot be easily reversed.

What is the difference between a mixture and a new substance formed by mixing?

In a mixture, the original materials are still present and could potentially be separated, like sand mixed with gravel or salt dissolved in water. When a new substance forms, the original materials have combined and changed in a way that produces something with different properties. Baking soda and vinegar react to form new substances; you cannot get the original baking soda and vinegar back from the foam.

How can active learning help students understand material mixing?

Hands-on mixing investigations let students observe changes in real time and generate genuine questions: why does this bubble? why does this get hard? why does this taste different? These questions are the starting point for scientific thinking. When students mix materials themselves and record what they observe, they build a personal evidence base for understanding the difference between physical mixing and chemical change.

Is oobleck a liquid or a solid?

Oobleck is a non-Newtonian fluid, which means it behaves like a solid when force is applied quickly and like a liquid when force is applied slowly. Hitting it sharply makes it resist like a solid, but letting your finger press in slowly causes it to flow. This unusual behavior comes from how cornstarch particles interact with water under pressure and makes oobleck a vivid example of how mixing can produce properties neither original material had on its own.