ALEX Resources

   View Standards     Standard(s): [SC2015] PS8 (8) 2 :

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.

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.

   View Standards     Standard(s): [SC2015] PS8 (8) 2 :

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.

[SC2015] PS8 (8) 5 :

5 ) Observe and analyze characteristic properties of substances (e.g., odor, density, solubility, flammability, melting point, boiling point) before and after the substances combine to determine if a chemical reaction has occurred.

In this lesson, students will use test liquids on different known powders and observe their reactions. Then students will use these characteristic chemical changes to help them identify an unknown powder.

Students will be able to identify and control variables to develop a test to identify an unknown powder. Students will be able to explain that a substance reacts chemically in characteristic ways and that these characteristics can be used to identify an unknown substance.

   View Standards     Standard(s): [SC2015] PS8 (8) 2 :

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.

In this lesson, students will be introduced to the idea that water has a slightly positive charge at one end of the molecule and a slightly negative charge at the other (a polar molecule). Students view animations, make illustrations, and use their own water molecule models to develop an understanding of how the polar nature of water molecules can help explain some important characteristics of water.

Students will be able to explain, on the molecular level, what makes water a polar molecule. Students will also be able to show, in a drawing, that the polar nature of water can explain some of water’s interesting characteristics and help explain its evaporation rate compared to a less polar liquid.

   View Standards     Standard(s): [SC2015] PS8 (8) 2 :

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.

In this lesson, students will observe several phenomena related to the polarity of water molecules. They will observe a demonstration of a paper clip being placed on the surface of the water. Students will place drops of water in an already-filled test tube and on the surface of a penny. They will compare the way water behaves with the less polar liquid isopropyl alcohol and will see how detergent affects water’s surface tension. Students will relate these observations to an explanation of surface tension at the molecular level.

Students will be able to explain, on the molecular level, the effects of polarity on water’s surface tension.

   View Standards     Standard(s): [SC2015] PS8 (8) 2 :

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.

In this lesson, students will make a 2-D model of a salt crystal and use water molecule cut-outs to show how water dissolves salt. After seeing an animation of water dissolving salt, students will compare how well water and alcohol dissolve the salt. They will relate their observations to the structure of salt, water, and alcohol on the molecular level.

Students will be able to explain, on the molecular level, why water can dissolve the salt. Students will be able to identify the variables in their experiment. Students will also be able to explain why a less polar liquid, such as alcohol, is not good at dissolving salt.

   View Standards     Standard(s): [SC2015] PS8 (8) 2 :

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.

In this lesson, students will observe the dissolving of the sugar coating from an M&M when it is placed in water. Students will then help design an experiment to see if the type of liquid the M&M is placed in affects how much of the coating dissolves.

Students will be able to explain, on the molecular level, how the polar characteristic of water and sugar interact so that water dissolves sugar. Students will be able to identify and control the variables in their experiment. Students will also be able to explain why a nonpolar liquid, such as mineral oil, is not good at dissolving sugar.

   View Standards     Standard(s): [SC2015] PS8 (8) 2 :

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.

In this lesson, students will observe a solubility test between salt and sugar. They will then be presented with four known crystals and an unknown. Based on the solubility demonstration, the class will design a solubility test to discover the identity of the unknown.

Students will be able to identify and control variables when designing a solubility test. Students will be able to explain why different substances dissolve to different extents in water.

   View Standards     Standard(s): [SC2015] PS8 (8) 2 :

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.

[SC2015] PS8 (8) 4 :

4 ) Design and conduct an experiment to determine changes in particle motion, temperature, and state of a pure substance when thermal energy is added to or removed from a system.

In this lesson, students will design an experiment to see if temperature affects the amount of dissolving of the sugar coating of an M&M.

Students will be able to identify and control variables to design an experiment to see whether the temperature of a solvent affects the speed at which a solute dissolves. Students will be able to explain, on the molecular level, why increasing temperature increases the rate of dissolving.

   View Standards     Standard(s): [SC2015] (2) 1 :

1 ) Conduct an investigation to describe and classify various substances according to physical properties (e.g., milk being a liquid, not clear in color, assuming shape of its container, mixing with water; mineral oil being a liquid, clear in color, taking shape of its container, floating in water; a brick being a solid, not clear in color, rough in texture, not taking the shape of its container, sinking in water).

[SC2015] (5) 3 :

3 ) Examine matter through observations and measurements to identify materials (e.g., powders, metals, minerals, liquids) based on their properties (e.g., color, hardness, reflectivity, electrical conductivity, thermal conductivity, response to magnetic forces, solubility, density).

[SC2015] PS8 (8) 2 :

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.

Matter is anything that has mass and takes up space. That is why mass and volume are the properties of matter.

The classroom resource provides a video that will describe the properties and characteristics of matter. This resource can provide background information for students before they conduct their own investigations. There is also a short test that can be used to assess students' understanding.