Unit Plans: Earth’s Climate Changes

Are you feeling overwhelmed by the amount of content in this issue? Or are you wondering how you can integrate these resources into your own classroom? We’ve created a unit plan for Grades K-2 and 3-5 using the resources in this issue of Beyond Weather and the Water Cycle. The units are modeled after a learning cycle framework built around five key steps — Engage, Explore, Explain, Expand, and Assess (or Evaluate).

The learning cycle

The Learning Cycle. Illustration from the Ohio Resource Center for Mathematics, Science, and Reading.

Grades K-2 and 3-5

Summary of Purpose for the Unit
This unit is designed to provide elementary students with the opportunity to investigate how the annual rings in trees help scientists learn about past climates. It uses hands-on experiences and nonfiction text to answer the question How do trees help scientists learn about the past?

One unit plan is provided for both grade bands. Teachers can modify the experience by selecting lessons and books that best support their students.

Standards Alignment

National Science Education Standards: Science Content Standards
Science content standards are found in Chapter 6 of the National Science Education Standards.

Science as Inquiry (Grades K-4)

  • Ask questions about objects, organisms, and events in the environment
  • Employ simple equipment and tools to gather data and extend the senses
  • Use data to construct a reasonable explanation
  • Communicate investigations and explanations

Science as Inquiry (Grades 5-8)

  • Use appropriate tools and techniques to gather, analyze, and interpret data
  • Develop descriptions, predictions, and models using evidence
  • Think critically and logically to make the relationships between evidence and explanations
  • Recognize and analyze alternative explanations and predictions
  • Communicate scientific procedures and explanations

IRA/NCTE Standards for the English Language Arts
View the standards at http://www.ncte.org/standards.

1 – Students read a wide range of print and nonprint texts.

3 – Students apply a wide range of strategies to comprehend, interpret, evaluate, and appreciate texts.

4 – Students adjust their use of spoken, written, and visual language (e.g., conventions, style, vocabulary) to communicate effectively with a variety of audiences and for different purposes.

5 – Students employ a wide range of strategies as they write and use different writing process elements appropriately to communicate with different audiences for a variety of purposes.

8 – Students use a variety of technological and information resources to gather and synthesize information and to create and communicate knowledge.

11 – Students participate as knowledgeable, reflective, creative, and critical members of a variety of literacy communities.

12 – Students use spoken, written, and visual language to accomplish their own purposes.

Unit Outline


Introduce the unit question, How do trees help scientists learn about the past?


In this phase, students should have opportunities to examine cross sections of trees (sometimes called “tree cookies”) and make observations about the annual rings.

Note: Physical specimens are ideal, but pictures of cross sections could be substituted. Avoid using strips of paper or other representations that do not resemble a tree trunk – they are too abstract for students at this phase.

Allow students to determine what types of data to collect. Should they count the rings? Measure them? Draw a diagram? Describe the pattern of light and dark rings? Instead of providing these ideas, consider giving cross sections to the students and asking them to make careful observations and record them in their science notebooks.

After students have observed the cross sections and recorded data in their notebooks, ask them to analyze their evidence. What kind of conclusions can they draw about the trees from these sections, and what evidence supports their conclusions? Help students link the evidence (their observations) to their conclusions, but allow the students to direct the conversation.

Students should record their evidence and claims in their science notebooks. A T-chart is a useful graphic organizer for this purpose. Allow time for students to share their conclusions and evidence with each other, taking care to help students deal with alternative explanations.


In this phase, students will develop greater expertise and answer the unit question. Begin by reading our Feature Story, Can You Read a Tree?. This nonfiction text introduces students to the nearly 5,000-year-old bristlecone pine, Methuselah, and explains how annual rings help scientists learn about past climates. You might wish to target the reading comprehension skill of questioning by using one of the lessons highlighted in Lessons about Asking, Answering Questions in conjunction with the Feature Story. Books about trees from our virtual bookshelf may also be helpful at this time.

After reading the story, have students return to the cross sections or pictures used in the Explore phase and re-examine them in light of what they’ve learned from the text. You may want to further direct observations by using procedures and resources from lessons highlighted in the article Lessons about Earth’s Past Climates. Lessons for primary students emphasize qualitative observations and counting of annual rings, while older students compare cross sections to temperature and rainfall data to explain the differences in the widths of rings.

All students, regardless of age or type of data collected, should add to their evidence and conclusions recorded in their science notebooks. Again, allow students time to share their conclusions and evidence with each other.

Finally, students will answer the unit question, How do trees help scientists learn about the past? This may be accomplished in any number of ways, depending on time, student abilities and needs, access to technology, and literacy goals addressed. Students might:

  • Draw a picture of their cross section and explain what they’ve learned about the tree’s history from it and the books they’ve read.
  • Write a letter from the vantage point of a scientist. In the letter, explain to another scientist what they’ve learned from the cross-section.
  • Create a glog (online poster) with a picture of the cross section and other images and notes that explain what was learned.
  • Create a timeline (either on paper or online through a tool like Capzles) illustrating events in the tree’s history. Include a paragraph describing the evidence that supports the conclusions. In Capzles, folders can be created to house the image or slide that explains the event and the supporting evidence.
  • Write a series of directions for younger students explaining how to study a tree’s cross sections and what can be learned from them.


This unit can be extended in a number of directions, depending on student interests. Here are just a few possibilities:

  • Learn more about Methuselah and bristlecone pines. Students might study the adaptations that allow the pines to live for thousands of years in a fairly harsh environment.
  • Learn about other old trees, such as giant sequoias or redwoods.
  • Study other types of evidence that scientists use to reconstruct past climates, including fossils and ice cores. Supporting lessons can be found in the article Lessons about Earth’s Past Climates.


This unit provides opportunities for both formative and summative assessment.

Formative Assessment

Formative assessment is conducted throughout the unit. For example:

  • Observation of students’ participation in class activities throughout the unit will provide insight into their current understanding and engagement with the topic.
  • Observation of students as they examine the cross sections and record data will illustrate the need to pose guiding questions to focus their efforts. It will also provide insight into the amount of support students need as they collect data.
  • Students’ entries in science notebooks will show how well they can draw conclusions and support those conclusions with evidence.
  • Listening to students’ questioning strategies while reading the Feature Story will help determine how much support they need with this strategy.

Summative Assessment

Students’ work for the final assignment serves as summative assessment for the unit. Student work can be assessed with a rubric that includes criteria for scientific accuracy, use of vocabulary, and overall quality of work.

This article was written by Jessica Fries-Gaither. Jessica is an education resource specialist at The Ohio State University and project director of Beyond Penguins and Polar Bears. She has taught in elementary and middle school settings. Email Jessica at beyondweather@msteacher.org.

Copyright July 2011 – The Ohio State University. This material is based upon work supported by the National  Science Foundation under Grant No. 1034922. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. This work is licensed under an Attribution-ShareAlike 3.0 Unported Creative Commons license.

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