What Explains Similarities and Differences Between Organisms?

What Explains Similarities and Differences Between Organisms?

This module is currently being field tested and is not available for purchase.

WHAT EXPLAINS SIMILARITIES AND DIFFERENCES BETWEEN ORGANISMS? is part of Smithsonian Science for the Classroom, a curriculum series by the Smithsonian Science Education Center. It is aligned to a group of grade 3 standards. It has a focus on life science with a secondary focus on earth and space science. In this module, students:

  • Make observations of variation in traits in Wisconsin Fast Plants and analyze data for patterns of inheritance
  • Collaboratively plan, carry out, and analyze the results of fair tests to see the effect of environmental variables on plant traits
  • Analyze average temperature and precipitation data for a range of cities to uncover patterns of climate zones
  • Develop a model that represents the stages common to all organisms’ life cycles
  • Analyze data from a study on how bees’ preference for certain flower colors gives plants a reproductive advantage
  • Construct an explanation for why guppies in some streams are bright orange while others are dull


Below are digital resources that support teaching of this module.

Lesson 1: Alike and Different

Family Letter

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Prior to starting What Explains Similarities and Differences Between Organisms? share the Family Letter with students’ caregivers. Indicate how they should submit responses to the letter.


Lesson 2: Plants Have Parents Too

Smithsonian Zoo News>

This website provides articles about the animals at the National Zoo. Scroll through the articles or use the search function to find articles about parents and offspring.


Lesson 3: Nature and Nurture

Environmental Factors (1:02 minutes)

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This video shows several environmental factors that could affect plant growth, including rain, sun, snow, wind, and nutrients.


Lesson 5: Pen Pal Plants

Weather Words

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This file provides descriptive terms for a set of summer temperature and precipitation conditions.


Lesson 6: Weather or Not

Summer Temperature Graph for Washington, DC

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This bar graph shows the average summer temperature in Washington, DC from 1998-2017.


Lesson 7: Comparing Climates

Köppen Climate Map

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This map of North America uses color to show the range of climate zones as well as the location of 16 cities.


Lesson 8: It’s Alive

Milkweed Eggs

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This image offers students a high resolution visual for use in observing the milkweed eggs. 


Lesson 11: Snapdragon Science

Snapdragon Study

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This PDF slideshow introduces students to the snapdragon research taking place at the Rocky Mountain Biological Laboratory. It provides visual support for introducing the central phenomenon.


Lesson 12: Busy Bees


This simulated field study allows students to conduct data based on a real-world investigation conducted at the Rocky Mountain Biological Laboratory. 


Lesson 14: Guppy Mystery Part 1

Field Site with Dull Guppies (1:05)

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This video goes underwater to show guppies swimming in a stream.


Trinidadian Streams and Guppies

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This file contains a map of Trinidad and Tobago and photos of the field site, scientists at work, and the guppies in the study.


Field Notes

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This PDF provides students with field note data taken from male offspring of guppies collected from the stream.

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