Lesson - Bend a Bone

Imagine being able to bend a bone! You can make a hard chicken bone turn rubbery with a little help from science. This lesson will focus on physical changes caused by a chemical reaction.

You’ll Need:

·  Drinking Glass

·  Chicken Wing Bone (cooked)

·  Vinegar

·  Observation worksheet

The chicken wing is make up of two parts: 1) short part with a single bone; 2) triangular-shaped tip with two smaller bones. Use the thinnest bone from the wing tip. Separate the two sections of a cooked chicken wing. Peel the skin and meat off the bone. Wash off the bone. Place one end on a table and push down gently on the other end. The bone doesn’t bend because it’s strengthened with a hard material called calcium carbonate. You may be surprised to learn that you can dissolve or break down this hard material using another kind of matter called an acid.

There are many different kinds of acids, some weak and some strong. Acids share the same special characteristics when dissolved in water: a sour taste, the ability to break down certain materials like calcium carbonate and metals, and the ability to conduct electricity. It’s weak acids in foods, like lemons, that make them taste sour. It is a weak form of acid in your stomach that helps break down the foods you eat. For this activity you’ll use a weak acid – vinegar. Pour enough vinegar into the glass to cover the chicken bone. Look closely. You’ll see tiny bubbles on the bone. That’s the acid already at work attacking the calcium carbonate material in the bone.

After two days, drain the glass and add fresh vinegar. On the fourth day, test the bone again by placing one end on the table and gently pressing down on the other end. If the bone doesn’t bend easily, return it to the vinegar bath. Continue checking the bone at two-day intervals until it bends easily. How long will it take for hard bone to turn rubbery? That depends on how thick the bone is and how much calcium carbonate material has to be dissolved. But it should bend easily within a week.

Lesson – Mold Me Again and Again

This lesson focuses on physical changes to matter. Students should recognize that a reversible physical change occurs as the students mold their clay into different shapes; however, the matter itself remains the same. So, they should conclude that some matter can change physically without changing its type.

Materials:

à  chunk of modeling clay

à  Worksheet: Mold Me Again and Again

Procedure:

  1. Before you distribute the clay, ask the students to describe its attributes. (What colour is it? How does it feel? What shape is it? Describe its size.) Write their observations on the board.
  2. Have students complete the activity sheet as they explore with their modeling clay.
  3. Challenge students to explore how many ways they can change the clay physically. (There should be an infinite number of ways!)
  4. Bring the class back together. Ask:
  5. What are some shapes you made with the clay?
  6. At any time did the clay change from a solid to another state of matter?
  7. Could you mold the clay back to its original shape?
  8. What other solids can you change physically?
  9. Would you need any tools to change it?

Lesson – Making Ice Cream

This lesson focuses on both chemical and physical changes to matter. First, a non-reversible chemical change occurs as students add sugar and vanilla to the milk. Second, a reversible physical change occurs as the students turn the liquid into a semi-solid.

Materials:

à  Milk, sugar, vanilla, small Ziploc bags, large Ziploc bags, ice, salt, Making Ice Cream Worksheet and instructions

Procedure:

à  Have students follow the procedure outlined on their worksheet and answer the questions.

à  Remind students to be thinking about both chemical and physical changes to matter and the reversible and non-reversible properties of each of those.

à  Once the students have completed the worksheet. Have them EAT their ice cream while discussing the chemical and physical properties that they manipulated.