Positively Popcorn

Adapted from a Lesson Developed by Janie Scronce

Objectives:

Objective 3.01
Determine three states of matter:
- Solid.
- Liquid.
- Gas.

Objective 3.02
Observe changes in state due to heating and cooling in common materials.

Materials:

• 1 popcorn popper (bubble popper is better so students can see process of corn popping)
• 1 bottle of cooking oil
• 1 bag of popcorn kernels
• The Popcorn Dragon by Jane Thayer (William Morrow and Company; ISBN: 0688083404)
• class set of sandwich bags with several unpopped kernels in each (1 per pair of students)
• sandwich bag full of popped kernels
• Paper towels
• Drawing paper
• Crayons and/or markers

Lesson Plan:

Engagement:

Hold up a bag with several popcorn kernels. Ask students a series of questions such as what is this? How do you know? Have you ever eaten it?

Hold up a bag with several pieces of popped popcorn. Ask students the same series of questions again.

Ask students if they know how popcorn goes from being a kernel to a piece of popcorn. Have the students brainstorm ideas.

Read the story The Popcorn Dragon by Jane Thayer

Exploration:

• Distribute a sandwich bag of unpopped kernels to each pair of students.
• Have the students make as many observations about the kernels as they can and write those in their science notebooks.
• Next, add oil and kernels to the popper and turn it on. (Remind students not to touch the popper because it is hot)
• Have students record as many observations as they can about the popcorn as it pops. What changes do they notice inside the popper?
• As they watch the popcorn pop: Inside each kernel is a tiny bit of water. When heat is added to the water, what do you think will happen? Why?
• Give each pair of students a paper towel with some of the popped popcorn on it. Have them record as many observations as possible about the popped popcorn.
• Have students compare and contrast the unpopped kernels with the popped popcorn.

Explanation:

Ask students questions about what they observed and learned from exploring the kernels and popped popcorn and watching the popcorn actually pop. Possible questions include:

• Now that everyone has made their observations what were some things that you wrote about the unpopped kernels?
• What about the popped popcorn?
• Based on what we have learned about solids, liquids, and gases, which category would you put the kernels in? What makes you say that?
• Describe what you saw as the popcorn popped.
• Based on your observations, can someone explain how they think the corn changed from kernels into popcorn?
• How is what we did with the popcorn like what the dragon did to the popcorn?
• When was our popcorn a solid? What makes something a solid?
• Where was the liquid in our popcorn? What happened to it? Why?
• When did we see a gas during this activity? Why was it so important?
• How was the gas different than the liquid?

Inside of each peice of popcorn is a tiny drop of water. When heat is added, the water changes from liquid into a gas (steam). When the pressure of the steam becomes to great, the popcorn kernel bursts open to form a piece of popcorn.

Expansion:

Set several popcorn kernels out in the sun for several days and then try to pop them.

• What differences do we observe in how the popcorn pops?
• Based on what we have learned about popcorn, what could explain the difference?

Teacher note: Setting the kernels in the sun will cause them to dry out. With less water they will be difficult to pop.

Evaluation:

• Have students draw a series of illustrations showing how the popcorn pops. They should label a solid, liquid, and gas within their pictures.
• Have students write a written explanation of how the dragon was able to cause the popcorn to pop including the words solid, liquid, and gas in their explanation.