Clean Pennies - Physical Change
Curriculum Tie: * Science
Objective 3Group Size:
Individual| | Summary:
Students will use dirty pennies to observe physical change. Main Curriculum Tie: Science - 5th Grade
Standard 1 Objective 2
Evaluate evidence that indicates a physical change has occurred.Materials: * Dirty pennies * Clean Pennies data sheet (pdf) * Safety goggles * Cups * Salt * Vinegar * Paper towel * Paper clipsAdditional ResourcesBooks * Writer’s Express: A handbook for young writers, thinkers, and learners, by David Kemper, et.al.; ISBN 0669471658 * Kitchen Science with over 50 Fantastic Experiments, by Chris Maynard (DK Publishing); ISBN 0-7894-6972-3Attachments * clean_pennies.pdfWeb Sites * USOE Science Some good ideas on the USOE science site for ELL students Background For Teachers:Each student needs a penny that is no longer shiny. If the pennies you have are too clean, oxidize the surface in the following manner. Place all the pennies into a cup and pour vinegar over the top. After coating them with vinegar, spread the pennies out on a paper towel to dry overnight. By the time they are dry you will see a green-colored substance called malachite.When the salt and vinegar are combined, they form a very small amount of hydrochloric acid. This acid removes oxidation from pennies. Removing the copper oxide is a chemical change. The copper molecules in the vinegar and salt solution settle on paper clips after a period of time, but wipe off easily. This is not a chemical change. If the cleaned pennies are allowed to sit without rinsing them off, more malachite forms.Intended Learning Outcomes: 1. Use Science Process and Thinking SkillsInstructional Procedures:Invitation to Learn Today we are going to do an activity with money and chemicals. The chemicals are sodium chloride and acetic acid (or salt and vinegar).Instructional Procedures 1. Give each student a dirty penny. Observe pennies. Stress the importance of using all the senses, except for taste. Students record observations on the Clean Pennies data sheet. 2. Pass out goggles. Students should keep the goggles on until the cups are put away in step six. Give each pair of students a cup with a small amount of salt in the bottom. Students place the pennies in the cup. Allow students to rotate cups. Ask what changes to the penny they see. (none) 3. Add a small amount of vinegar to each of the cups. Allow students to rotate cups and observe changes. 4. Pennies will become bright pink and copper colored. All the discoloration may not be removed, but most pennies will show a dramatic difference. 5. Remove pennies and place them on a paper towel to dry. Continue observations. 6. Place a paper clip in each cup of vinegar and salt solution. Leave the paper clip in the solution overnight. After cups are put away, remove goggles. 7. Observe paper clips next day. Wear safety goggles to avoid splash danger. Allow students to remove the paper clip from solution and handle it. The copper coating will rub off easily. Ask students if the paper clip’s change to copper-colored was a chemical or physical change. (It was a physical change. No new substance was formed. The copper was there all the time—dissolved in the solution.)Extensions: * Allow students with special needs to list or draw examples of chemical change instead of writing a paragraph. * Make a list of Important Science Words to use in the assigned paragraph. * Allow students with special needs to dictate their paragraph to another student, an aide, or the teacher. * To introduce the idea of physical properties, have each student bring an object from home. Each student describes a number of physical properties, such as color, shape, texture, etc. Other students take turns guessing the identity of the item.Family Connections * Have a mold...