Can You Identify the Mystery Substance? An Inquiry-Based Lab Activity

Learning Resource Type

Lesson Plan

Subject Area

Science

Grade(s)

Overview

Students will begin this inquiry-based lesson by accessing their prior knowledge about the distinguishing characteristics of different substances. Using ideas from the students, the teacher will create a list of physical and chemical properties that can be used to recognize different substances. Next, the teacher will assist the students in planning an investigation that will test methods to determine the identity of substances based on their characteristic properties. Lastly, students will carry out the investigation they planned with the aim of identifying "mystery" substances using their unique physical and chemical properties.

This lesson results from a collaboration between the Alabama State Department of Education and ASTA.

Science (2015) Grade(s): 8

SC15.8.2
Plan and carry out investigations to generate evidence supporting the claim that one pure substance can be distinguished from another based on characteristic properties.

Vocabulary

Investigation
Claims
Evidence
Substance
Matter
Composition
Property
Element
Compound
Pure substance
Characteristic properties
Physical property (includes, but not limited to, color, odor, density, melting point, boiling point, solubility)
Chemical property (includes, but not limited to, flammability, reactivity with water, pH)

Knowledge

Students know:

A substance is matter which has a specific composition and specific properties.
Every pure element is a substance. Every pure compound is a substance.
Pure substances have characteristic properties.
Characteristic properties are physical or chemical properties that are not affected by the amount or shape of a substance.
Characteristic properties can be used to identify a pure substance.
Physical properties of a substance are characteristics that can be observed without altering the identity (chemical nature) of the substance.
Color, odor, density, melting temperature, boiling temperature, and solubility are examples of physical properties.
Chemical properties of a substance are characteristics that can be observed but alter the identity (chemical nature) of the substance.
Flammability, reactivity with water, and pH are examples of chemical properties.

Skills

Students are able to:

Identify the phenomena under investigation, which includes pure substances and their characteristic properties.
Identify the purpose of the investigation, which includes demonstrating that one pure substance can be distinguished from another based on characteristic properties.
Develop a plan for the investigation individually or collaboratively.
Describe factors used in the investigation including appropriate units (if necessary), independent and dependent variables, controls and number of trials for each experimental condition.
Perform the investigation as prescribed by the plan.
Make a claim, to be supported by evidence, to support or refute an explanation or model for a given phenomenon, including the idea that one pure substance can be distinguished from another based on characteristic properties.
Identify evidence to support the claim from the given materials.
Evaluate the evidence for its necessity and sufficiency for supporting the claim.
Use reasoning to connect the evidence and evaluation to the claim that one pure substance can be distinguished from another based on characteristic properties.

Understanding

Students understand that:

Each pure substance has characteristic physical and chemical properties (for any bulk quantity under given conditions) that can be used to identify it.
Pure substances can be distinguished from other pure substances based on characteristic properties.
Substances react chemically in characteristic ways. In a chemical process, the atoms that make up the original substances are regrouped into different molecules, and these new substances have different properties from those of the reactants.

Scientific and Engineering Practices

Planning and Carrying out Investigations

Crosscutting Concepts

Patterns

Primary Learning Objectives

Students will describe and identify physical and chemical properties of a substance.
Students will plan an investigation to distinguish one substance from another based on its characteristic properties.
Students will carry out an investigation to gather evidence supporting the claim that one substance can be distinguished from another based on its physical and chemical properties.

Procedures/Activities

Before Strategy/Engage: 15 minutes

1. The teacher should give the students two minutes to respond to this quick write prompt: "How can you distinguish one substance from another substance?"

2. After the students write their answers individually, the teacher should allow students two minutes to discuss their answers with a partner or group. The students should record any new ideas on their list.

3. After students discuss their answers, the teacher should ask student volunteers for their responses and create a class T-chart, labeled "Physical Properties" on the left and "Chemical Properties" on the right. As students share their responses, the teacher should add each idea on the appropriate side of the chart.

Note: Physical properties can be determined by observing a substance without changing its composition. Examples of physical properties include color, solubility, freezing point, and boiling point. Chemical properties are determined by the substance's reaction to other substances or other chemical changes. Examples of chemical properties include reactivity with other substances, flammability, and chemical stability.

During Strategy/Explore & Explain: 30 minutes

1. Next, the teacher should tell the students that they will need to plan an investigation to test how one substance could be distinguished from another substance based on its characteristic properties. Depending on the students' experience in planning investigations, the teacher may give the students free rein to plan the investigation with their group members or guide students to plan an investigation similar to the one detailed in the remainder of the lesson plan.

2. Before beginning the investigation, the students will need to plan each step of the scientific experiment, which includes the following:

The problem or question that the experiment will attempt to answer
A hypothesis that describes what the students think will occur in the investigation (usually formatted as an If...then...because... statement)
The materials that will be needed to carry out the investigation
An experimental design that describes the variables in the investigation and the procedures that will be followed to complete the experiment
A plan to collect data such as a chart, table, or graph

The students can write this information on notebook paper or use a planning sheet, such as "Scientific Method Flow Chart" from biologycorner.com.

After Strategy/Explain & Elaborate: 60 minutes

Note: The following procedures are an example of a scientific investigation that will meet the objectives of the selected standard. Depending on the experiment the students planned in the during strategy, the specifications of each individual experiment may vary.

1. Students should be divided into collaborative groups of approximately four students each. The teacher should give each student a copy of the "Mystery Substance Data Table". Each group of students will need the required materials to carry out the scientific investigation.

2. The students should begin by observing the five mystery substances and recording the color, relative particle size (using a magnifying glass, if needed), and state of matter of each substance on their data table.

3. The students should test each mystery substance for magnetic properties. The students should place one scoop of the mystery substance on a sheet of paper, then move the magnet underneath the paper (the magnet should not directly touch the mystery substance). Students should record findings in their data table (magnetic or not magnetic). Complete this procedure for all mystery substances.

4. The students should use a graduated cylinder to measure 5 mL of water. The students should pour the 5 mL of water into a clean test tube, then place one scoop of the mystery substance into the test tube with the water. The students can swirl the test tube to mix the substance with the water or use a stirring rod. Students should record their findings in the data table (insoluble, partially soluble, or soluble). Complete this procedure for all mystery substances.

5. The students should use a graduated cylinder to measure 5 mL of vinegar or acetic acid. The students should pour the 5 mL of the selected acid into a clean test tube, then place one scoop of the mystery substance into the test tube with the water. The student can swirl the test tube to mix the substance with the selected acid or use a stirring rod. Students should record their findings in the data table (if the substance reacts with the acid, the students should describe the appearance of the reaction). Complete this procedure for all mystery substances.

6. After all groups complete the investigation, the teacher should ask the students to respond to the following questions, which will serve as the conclusion of their scientific investigation. The teacher may wish for the students to respond verbally and discuss their answers with their groups or to write their answers on paper for the teacher to review at the conclusion of the lesson.

Did your investigation fully answer the question you developed prior to the experiment? Would you need to perform any additional tests to answer your question?
How could you use the data collected during this investigation to determine the identity of the mystery substances?
Are you able to identify any of the mystery substances based on the physical and chemical properties discovered during the investigation? If you were not able to determine the identity of a particular mystery substance, what additional tests would you need to perform to discover the substance's identity?

Assessment Strategies

Formative Assessment: The teacher will informally assess students' understanding of the concept in the quick write and discussion portion of the before strategy. In the during and after strategies, the teacher should informally assess students' abilities in planning and in completing a scientific investigation. The teacher should ensure that students follow the specified procedures and safety requirements of the investigation.

Summative Assessment: The teacher should formally assess students' understanding of the lesson objectives at the conclusion of the investigation. Each student should be able to describe how their planned investigation demonstrated that one substance can be distinguished from another based on characteristic properties. Each student should also be able to identify ways the investigation could be extended or improved in order to determine the identity of each mystery substance.

Acceleration

The teacher can identify students who will require acceleration strategies prior to teaching the lesson and appoint these students as "group leaders" during the investigation portion of the lesson. Students can expand upon the concepts of this lesson by developing additional tests that would help identify the mystery substances.

Intervention

The teacher should provide additional scaffolding to students requiring intervention strategies while planning the investigation in the during strategy. The teacher should provide assistance to students as they carry out the investigation to ensure the procedures are being followed accurately. At the conclusion of the lesson, the teacher could allow students to answer the conclusion questions verbally, rather than in a written format.

Total Duration

91 to 120 Minutes

Background/Preparation

Student Background Information: This lesson will introduce students to the concept of distinguishing substances from one another based on physical and chemical properties. This lesson does require students to possess background knowledge about the characteristic properties of substances. This concept relates to fifth grade Alabama Course of Study standard three. In addition, the selected standard for this lesson requires students to plan and carry out a scientific investigation. If students do not have experience in planning scientific experiments, the teacher may wish to spend additional time during this phase of the lesson to ensure students master this skill.

Teacher Background Information: Substances can be identified by their distinguishing characteristics, known as physical and chemical properties. Physical properties can be determined by observing a substance without changing its composition. Examples of physical properties include color, solubility, freezing point, and boiling point. Chemical properties are determined by the substance's reaction to other substances or other chemical changes. Examples of chemical properties include reactivity with other substances, flammability, and chemical stability.

The selected standard for this lesson requires students to plan and carry out a scientific investigation. Depending on the students' experience in planning investigations, the teacher may give the students free rein to plan an investigation or guide students to planning an investigation similar to the one detailed in the remainder of the lesson plan. However, the teacher should be sure to guide students to plan an experiment that can be carried out using available materials, space, and resources. The teacher may have to change the exact specifications of this lesson plan depending on the resources available in his or her specific classroom environment. As written, this lesson plan will require students to observe and mix different substances with water and an acid. Depending on available resources, the teacher could add additional steps to the experiment, such as testing the boiling point of the substances. The teacher should ensure students follow all safety precautions, including wearing safety goggles, never tasting or directly smelling substances, and only performing authorized experiments.

This lesson will require students to be divided into collaborative groups of approximately four students to carry out the investigation. The teacher may wish to set up the materials required for the investigation prior to the students completing the experiment or allow the students to assist in the setup.

Materials and Resources

Student Materials (per student)

Notebook paper

Pencil or pen

Scientific investigation planning sheet for before strategy: "Scientific Method Flow Chart" from biologycorner.com

"Mystery Substance Data Table"

Student Materials (per group)

Note: The following materials will be used in the investigation detailed in the after strategy, which is an example of a scientific investigation that will achieve the objectives of the selected standard. The required materials for each individual investigation may vary, depending on the specific experiment planned by the students in the during strategy.

10 test tubes

Test tube rack

Stirring rod

Magnet

Magnifying glass

Water

White vinegar or acetic acid (depending on availability)

Graduated cylinder

Measuring spoon or scoop

At least five mystery substances (include both solids and liquids) such as baking soda, iron filings, flour, sugar, corn starch, salt, vegetable oil, lemon juice, etc.

Note: To preserve the "mystery" of the substances, the teacher should label each substance as A, B, C, etc.

Teacher Materials

Chart paper or board

Approved Date

2016-12-28

Owner (Author)

habradley