Seasons

Lesson Rationale: The purpose of this lesson is for students to be able to explain how the seasons occur. Students will deconstruct their misconceptions and use scientific evidence to determine what causes the seasons. Prior to this lesson students should have investigated how the angle of sunlight effects the amount of heat. Students should also have investigated how the length of shadows in different seasons show how the sun rises higher in the sky during the summer.

1. Encourage and model the skills of scientific inquiry, as well as the curiosity, openness to new ideas and data, and skepticism that characterizes science.

2. Students should develop understanding and abilities aligned with the following concepts and processes: evidence, models and explanation.

Do Now: Using your pre-lab and knowledge from prior activities, what can you conclude about the interaction between the earth and the sun?

m Teacher says, “In class and your pre-lab we have started to explore the interaction between the earth and the sun. Today we are going to use this knowledge to explore how the seasons occur. To begin we are going to discuss what evidence we can use to figure out how the seasons occur. Then you will explore your ideas using models.”

m Teacher draws the following table on chart paper and students copy into notes:

Evidence	Initial Ideas	Evaluation of Initial Ideas	Conclusions

Discuss the do now. Teacher uses this to help students think about what they know. Students will use this evidence to generate initial ideas about how the seasons occur and to later evaluate those ideas. Teacher records answers (8 or 9 responses) in the first column of the table. (Student responses could include: 1. It's cold in winter and hot in summer. 2. The seasons happen on a regular schedule. 3. The strength of the seasons varies as you go north or south, but not as you go east or west. As you cross the equator, the seasons reverse. During winter in the Northern Hemisphere, it's summer in the Southern Hemisphere, and vice-versa. 4. The days are shorter, and nights longer, in winter than in summer. 5. The Sun rises higher in summer than in winter. 6. The Sun seems to be the same size in winter as in summer.)

Lesson Body: m Teacher says, “Now, you will work in groups using a lamp and a mini globe, to generate ideas about how the seasons occur. Use the list of evidence to help you. Record your ideas in the second column of the chart.”

Teacher circulates to facilitate group work. Possible teacher questions: What evidence supports your hypothesis? What observations could you make from earth if your model were true?

As a whole class, share ideas from the group work. Teacher records responses in the second column. (Possible responses: The seasons are caused by: 1. changes in the distance between the earth and the sun 2. changes in the earths angle or tilt 3. Changes in the angle of the sunlight 4. the earth wobbling changing the angle the sun hits it.)

Teacher says, “In your groups, look at each idea and determine if it is possible for it to be true, using the evidence. In the third column write whether it is true or not and the evidence you used to support your answer. You can use the models and your prelab to help you.”

Closure: m Teacher facilitates a class discussion about the student evaluations of the ideas. Possible Teacher questions: If this idea were true, what would be observable from earth? What would we experience? Is this idea supported by the evidence? Does this idea contradict the evidence? The goal of this discussion is to arrive at the conclusion that seasons are caused by the tilt and revolution of the earth. The teacher’s role in this discussion will vary depending upon the students prior knowledge and higher level thinking skills. Possible questions to facilitate reaching a conclusion: What do you know about the motion of the earth that will help determine which idea is possible? (since the most common and deeply held misconception is that the sun is farther away from the earth in the winter and closer in the summer, possible teacher questions to deconstruct this idea are: If this idea were true, would it be possible for the Northern and Southern hemispheres to experience different seasons? Why? If the sun were getting closer to the earth, what would we be able to observe?) The teacher could also use the models to help facilitate the discussion.