Engaging in Argument: Structure and Function in Terrestrial Animals and Plants | EL Education Curriculum

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LS G4:M2

Engaging in Argument: Structure and Function in Terrestrial Animals and Plants

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The Life Science Module represents three additional hours per week of instruction during the eight to nine weeks covered by Module 2 of our Grades 3-5 Language Arts Curriculum. Although the Life Science Modules can stand alone, each one connects with and complements Module 2 of the grade-level language arts module lessons. For the complete materials list or to learn more about how the Life Science Modules are aligned with the Language Arts curriculum, read the K-5 Language Arts Guidance Document found on the Tools page.

In the Grade 4 Life Science Module, students learn about different body structures of plants and animals and how those structures help an organism survive. Students answer the guiding question: "How do the internal and external structures of plants or animals function together as a system to help them survive well in a given habitat?" Students design a fictional animal and create an explanatory model to show how the animal's structures work together as a system to help the animal survive well. They also add plants from the animal's specific ecosystem to the model and explain the specialized structures of the plants. Students then write a paragraph to argue that the animal they designed can survive well in a given habitat.

To build enough understanding to successfully craft the argument and create the explanatory model, students first learn about a variety of internal and external structures in animals (Lesson Sequences 3-6) and then the internal and external parts of plants (the focus of Lesson Sequences 7-10). They also learn about how these structures function together as a system to help an organism get its needs met in a habitat. Because habitats are situated in larger ecosystems, students become experts on one of three ecosystems--the tundra, desert, or grassland ecosystem (Lesson Sequence 2). Students use their learning about the characteristics of the ecosystems and the specialized structures of plants and animals to understand how an organism can survive well.

Throughout the module, students engage in the Science and Engineering Practices (things that scientists and engineers do) by making explanatory models and engaging in arguments. Students also consistently use Crosscutting Concepts (concepts that link across various scientific disciplines), especially systems and cause and effect, to deepen their understanding of the content. Routinely, they track their learning in a student science notebook, and practice articulating, questioning, and refining their understanding in Scientists Meetings.

Although this Grade 4 Life Science Module was designed to work in concert with EL Education's Language Arts Grade 4 Module 2, it can also stand alone. The content of the Language Arts module complements the student learning about structure, function, and survival in the Life Science Module, and in both the Language Arts and Life Science Modules, students engage in similar protocols and do close reading.

Download this module below to access Getting Started materials, full NGSS Standards descriptions, Week-at-a-Glance charts, materials lists, the Student Science Notebook, and all lesson supporting materials.

Guiding Questions and Big Ideas

How do the internal and external structures of plants or animals function together as a system to help them survive well in a given habitat?

  • For both plants and animals, the internal and external structures of an organism function together to ensure that the organism is able to obtain food, grow, avoid predators, and reproduce. These functions are all essential to an organism being able to survive well.
  • Because all habitats have different hardships and available resources, the structures of the organism living there must be specialized for survival under those specific conditions. If any structure was removed from the organism, its system would be incomplete and it would not survive as well.

The Four Ts

  • Topic: Engaging in Argument: Structure and Function in Terrestrial Animals and Plants (NGSS Performance Expectations)
  • Task: Explanatory model of a fictional animal, including specialized structures and ability to survive in specified ecosystem
  • Targets:
    • NGSS Performance Expectations fully and explicitly taught and formally assessed: 4-LS1-1
    • NGSS Performance Expectations explicitly taught but only partially assessed: 4-LS1-2, 3-LS4-3
    • CCSS ELA reinforced throughout the module: RI.4.1, RI.4.2, RI.4.3, W.4.1, W.4.2, W.4.8, W.4.9, and SL.4.1
  • Texts:
    • "Aaron's Art Tip-18: Drawing and Painting Animals from Life" (video)
    • "Researching the Grassland, Tundra, and Desert Ecosystem"
    • "How Animals Move" (video)
    • "The Science of a Cheetah's Speed" (video)
    • "Fun Fur Facts"
    • "Flights of Fantasy"
    • "Scales: Coats of Armor"
    • "Animals with Skeletons on the Outside: The Exoskeleton"
    • "Roots, Stems, Leaves, Oh My!"
    • "Oceans of Grass"
    • "Seeds" (video)
    • "Seeds on the Move"

Content Connections

CCSS ELA Connections

This module is designed to address NGSS standards. But the module intentionally incorporates content, protocols, and skills that align with EL Education's Language Arts Grade 4 Module 2. Many of the animal defense mechanisms studied in EL Language Arts Grade 4 Module 2 are specialized structures that function to help an animal survive well in a specific habitat. Some of the animals studied in the Language Arts module come from the desert, tundra, or grassland ecosystems. In both the Language Arts and Life Science Modules, students also use similar protocols, including Back-to-Back and Face-to-Face and close readings.

In addition, students routinely have opportunities to read informational texts (CCSS ELA RI.4.1, RI.4.2, and RI.4.3) and write arguments and explanations (CCSS ELA W.4.1 and W.4.2). The student science notebook is an additional opportunity to practice informative writing and gathering evidence (CCSS ELA W.4.2, W.4.8, and W.4.9). The Scientists Meetings, which students participate in throughout the Life Science Module, provide students the opportunity to formally practice their speaking and listening skills while collaborating in whole group discussions (CCSS ELA SL.4.1).


Each unit file includes teacher materials and student-facing materials.


Survival Argument

In conjunction with the performance task, students construct an argument in response to the following question: "Does your designed animal have the necessary internal and external structures to survive well in a tundra, desert, or grassland ecosystem?"

Students use their explanatory model as evidence, as well as the information gathered in their student science notebook to help them provide scientific reasoning to justify their argument. This assessment aligns with NGSS Performance Expectations 4-LS1-1 and 3-LS4-3.

Original Student Investigations: Earthworm Sensory Input Investigation

Students plan and carry out an original investigation to answer the question "Does an earthworm respond to its environment even though we can't see its sensing structures?" First, students brainstorm a list of possible stimulus and decide which one to use in the investigation. They then plan and carry out the investigation, including multiple trials. They chart and evaluate their data in their student science notebook. This original student investigation aligns with NGSS Performance Expectations 4-LS1-2, as well as the Science and Engineering Practice of Planning and Carrying Out Investigations.

Original Student Investigations: Environmental Pressures Investigation

Students plan and carry out an original investigation where they observe that specialized structures affect the survival of an organism. Students plan and carry out an investigation to replicate environmental pressures on grass and radish plants. They record observations in their student science notebook of their experiment every few days over a period of seven days. At the conclusion of the investigation, students use their data to make meaning of the cause and effect relationship between environmental pressures and the grass and radish plants' survival. This original student investigation aligns with NGSS Performance Expectations 4-LS1-1, as well as the Science and Engineering Practice of Planning and Carrying Out Investigations.

Performance Task

Animal Design Challenge Explanatory Model

This performance task gives students the opportunity to showcase their deepened understanding of how the internal and external structures of plants or animals function together as a system to help them survive well in a given habitat. For this task, students design a fictional animal with realistic structures that enable it to survive well in a desert, tundra, or grassland ecosystem. They draw an explanatory model of the animal to explain how the specialized structures of the animal work as a system to support the animal's survival in the specified ecosystem. The explanatory model also includes the animal's habitat and explains how the surrounding plants also have specialized structures for surviving in the specified ecosystem. This task aligns with NGSS Performance Expectations 4-LS1-1 and 3-LS4-3.


For basic lesson preparation, refer to the materials list and Teaching Notes in each lesson sequence. The following are science specific materials that will require significant advance preparation. More information on quantities and specific instruction is in the materials list in each lesson sequence.

At least two weeks before beginning the Grade 4 Life Science Module.

  • Seed clear plastic cups with radish or grass seeds. Refer to the "Directions for Preparing Grass and Radish Plants for Experiment" below.
  • Order earthworms and prepare classroom habitat. Refer to the "Additional Resources" below for suggested vendors.
  • Ensure Google Earth is working on the computers available in your school lab.
  • Consider keeping other living organisms in the classroom so students can informally observe organisms.

Week 1

Lesson Sequence 1

  • Obtain a copy of A Bug's Life.
  • Create a teacher science notebook.
  • Copy and assemble the student science notebooks. Note: Not needed if your school has purchased the bound Student Science Notebooks.
  • Prepare the mock Google Earth Tour (or if the technology is available, create a Google Earth Tour).

Lesson Sequence 2

  • Find an object to represent a system (e.g., pencil, clothes pin, bicycle, etc.).
  • Create Plant and Animal cards.

Week 2

Lesson Sequence 3

  • Gather materials for earthworm observations, including earthworms, paper towel and plate or tray, banana, spray bottle with de-chlorinated water.
  • Gather materials for the Obtaining Food Structures Stations, including stopwatches, straws, spoons, tweezers, cups, binder clips, chopsticks, masking tape, staple removers, flat stones the size of a child's hand, cotton balls, plant material such as stems or leaves, tray with an assortment of "food items" such as beans, raisins, lentils, popcorn, etc. See materials list in Lesson Sequence 3 for specific quantities.

Week 3

Lesson Sequence 4

  • Gather materials for teacher and student earthworm investigation, including earthworms, petri dish or plate, wet paper towels, a small bottle of vanilla extract, spray bottle with de-chlorinated water, and sets of student stimuli materials as chosen by students (see Lesson Sequence 4 Teaching Notes for ideas).

Lesson Sequence 5

  • Gather materials for earthworm observation, including gloves, earthworms, wet paper towels, tray/observation plates, magnifying glasses.
  • Gather materials for guided chicken wing dissection, including chicken wing, gloves, safety goggles (optional), dissecting kit or scissors, tray/plates and materials to clean (soapy water, disinfecting wipes, sinks to wash hands etc.).
  • View and download the video "Life Science: Chicken Wing Dissection."

Week 4

Lesson Sequence 6

  • N/A

Lesson Sequence 7

  • Gather a variety of plants and plant parts, including plants with specialized structures, such as cacti or aloe, a variety of flowers and leaves, and seeds such as burrs, helicopters, or pea pods.
  • Obtain a whole grass plants with roots.
  • Gather, if possible, live plants from each ecosystem:
    • Desert plant: prickly pear cactus
    • Tundra plant: diamond leaf willow
    • Grasslands plant: coneflower

Week 5

Lesson Sequence 8

  • Gather materials for the environmental pressure experiment, including cups with grass plants, cups with radish plant, and graduated cylinder. Note: Grass and radish plants should be started before the module begins. See "Directions for Preparing Grass and Radish Plants for Experiment."
  • Gather materials for mimicking environmental pressures, such as metal spoon (trampling) or scissors (grazing).

Lesson Sequence 9

  • Gather materials for lima bean dissection, including lima bean (soaked for at least 12 hours), magnifying glasses, and tweezers.
  • Gather grass seeds (a few per pair).
  • Gather materials for germination bags including: clear plastic bags, paper towel, seeds (any combination of grass, green bean, corn, lima bean, barley, radish), permanent marker, water spray bottle, and stapler.

Week 6

Lesson Sequence 10 (optional; the investigations set up in Lesson Sequences 8 and 9 both need a week of observations before they can be revisited)

  • Gather a variety of seeds that use different dispersal mechanisms (e.g., bean, grass, lima bean, maple seeds/helicopter seeds, apple/fruit (apple cut in half to expose seeds), coconut, burdock, and dandelion.
  • Gather materials for constructing the engineering design challenge, including two or three seed models (e.g., packing peanuts, marbles, bingo chips, small oval rocks, buttons, washers of different sizes, beads, or any other small item that can be a mock seed), a variety of dispersal structures (e.g., Velcro(r), strips of paper, tape, plastic bags, paper clips, bubble wrap, tissue paper, coffee filter, or any other item that can be used as a mock structure), and materials for attaching and building such as tape, string, pipe cleaners, twist ties, and scissors.
  • Gather materials for testing the engineering design challenge, such as long plastic bin and fan (water dispersal), fan (wind dispersal), and wool glove (animal dispersal).

Week 7

Lesson Sequence 8

See above.

Lesson Sequence 9

See above.

Week 8

Lesson Sequence 11

  • Prepare materials for the summative assessment.
  • Prepare materials for the Animal Design Challenge explanatory model (the performance task).

Student Science Notebooks

The student science notebook plays a central role in the science classroom. This notebook is a place for students to track their learning and organize their evidence. Encourage students to take ownership of the notebook and use it to record all of their ideas and questions throughout the module, in addition to writing in responses to the formal prompts.

The science notebook is patterned after an "interactive notebook." When opened flat, the left-hand side of the notebook is primarily for instructions and prompts; the right-hand side is primarily for student responses and ideas. When copying and creating the notebook, be sure to staple correctly.

Students will use the notebook during every science class and return to it several times throughout the block. Consider the classroom systems and structures already in place to help students easily access and store their notebook.

Encourage students to use pencils, because they often will create detailed drawings and diagrams. As students return to and revise their ideas, have them lightly cross out changed thinking (rather than erasing) so their changes in thinking can be documented. Periodically, students may need to attach something to their science notebook. Use tape or staples (glue can make the pages stick together).

Periodically (once a week or so), collect the notebook to formatively assess students' understanding of the Disciplinary Core Ideas and Crosscutting Concepts as well as their ability to apply the Science and Engineering Practices. In each lesson sequence, the ongoing assessment box suggests parts of the notebook to focus on. Remember that the science notebook should not be used as a summative assessment. Rather, the notebook is a place where students are encouraged to try out new ideas, revise old ideas, and take risks.

For more information about the student science notebook, see the California Academy of Science, Teacher Perspectives: The Value of Science Notebooking.

Living Organisms in the Classroom

Science comes alive for students when there are real plants and animals in the classroom. EL Education encourages teachers to use living organisms in their classroom, and each life science module includes both formal and informal learning opportunities that incorporate live plants and animals. When done with careful thought and preparation, the close observation and study of living organisms not only teaches students about science and nature, but fosters an attitude of respect and kindness toward all living things.

To ensure the best learning experience with living organisms, it's important to plan ahead. First, familiarize yourself with the NSTA guidelines for the responsible use of live animals in the classroom. Then check up on local and state laws and regulations concerning the handling and transportation of animals, particularly non-native species. Most importantly, learn as much as you can about the particular plant or animal that you want to study. Take the time to have your students help you build a clean, safe and attractive habitat for the organism. The more you and your students learn about the safe handling of the organism, the better you will treat and care for the classroom visitor.

When planning classroom activities with a live organism, remember that the highest purpose is to promote observation and scientific curiosity, and instill an appreciation for the value of life. Under no circumstances should an activity cause an animal pain, deprive it of food or comfort, or expose it to harmful substances. Instead of "experimenting" with living things, help student discover ways to improve the organism's life by learning what it needs to thrive. It's not always necessary to have a formal research question. Close observation of an animal -- taking notes, asking questions, making hypotheses -- can be a powerful learning experience all its own.

A critical part of the planning process is deciding what to do with an animal after it leaves your classroom. If it's a native species, you could send the animal home with a student or release it into the wild. Non-native species require more forethought. If you buy the animal from a biological supply company, ask if they will take the animal back when you are done. If that's not possible, ask the supply company exactly where the animal was raised or collected. Contact a school in that area and see if a local science teacher would be willing to release the animal for you. The safe return of an animal to its home is an important lesson for your students to learn.

Science Background Information for Teachers

Below is the science background information about ecosystems and plant and animal structures, as well as their function, including adaptations to survive in harsh ecosystems. Use this background to help you effectively teach the science content of the Grade 4 Life Science Module. Refer to the sources and additional resources listed below for more information.


In this module, students learn about the internal and external structural adaptations that animals and plants use to survive and thrive in the following ecosystems:

  1. Grasslands: In the grassland ecosystem, grass is the dominant vegetation, with few trees and shrubs. Earth's major grasslands include the African savanna, the prairie in the North American Great Plains, and the Steppes of Eurasia. (The Grassland Biome) Grasslands have a wet and dry season. Grazing animals migrate in groups to access water and protect group members from predators. (Grasslands--WWF) Meanwhile, plants have specialized root structures to collect limited water and anchor themselves against strong winds. Fires are important to the grassland as they help recycle nutrients in the soil and reduce competition from woody plants (i.e., shrubs and trees). (Grasslands--National Geographic)
  2. Desert: Deserts are extremely dry and receive less than 10 inches of rain per year. Deserts are often very hot in the day and very cold at night. The Sahara Desert in northern Africa is the largest and most well-known desert in the world, but the Mojave Desert and Great Basin are deserts found in the western United States. In order to survive in the desert, many animals are nocturnal. They hide underground during the hot day and hunt for food during the cooler night. Some plants survive by storing water in their stems. (Desert) Animals often get their water intake from eating plants and seeds, though many plants are covered in spines or thorns to ward off these threats. (Desert Animal Survival)
  3. Tundra: Tundras are found in the polar regions of the earth, and are very cold and receive very low precipitation. Like deserts, tundras often receive less than 10 inches of precipitation, mostly in the form of snow. Furthermore, the soil is almost always frozen, a condition known as permafrost. During the Arctic summer, temperatures get high enough to thaw the surface layers of the permafrost. The water that is released finds low and flat areas and makes them very wet. So, despite the desert-like precipitation amounts, some of the tundra is covered with wetlands during the summer (Tundra) In order to survive in this ecosystem, animals often have smaller bodies and shorter limbs, so they require less energy to stay warm. They have thick fur, and in some animals their brown fur changes to white in the winter to better camouflage with snow. (Tundra Animals) Similarly, plants grow close to the ground and are often covered in fine hairs to reduce heat loss. (Plant Adaptations--Missouri Botanical Garden)

Even though these ecosystems are distinct, they share extreme conditions--including limited rainfall and extreme temperature variance.

Animal Structures

Most animals have several body systems that help them maintain stability in order to survive, grow, and reproduce. Each of these systems is made of organs that work together to perform its functions. The systems that students study in this module are as follows:

  1. Musculo-skeletal System: Invertebrates do not have bones; instead, they use muscles to control movement. In vertebrates, this system includes all of the muscles, bones, cartilage, tendons, and ligaments that allow an animal to move. The ability to control and direct movement is one of the most important differences between plants and animals.
  2. Digestion System: The digestive system is essential for animals to consume and break food down in order to absorb important nutrients. This is important because unlike plants, animals cannot make their own food; they must ingest food. In more complex animals this can include the mouth, stomach, intestines, and anus. Other animals just have a specialized gastric cavity where digestion takes place. In this module, students learn about the beginning of this complex system. They study the specialized structures found in the mouth, including teeth and other mouthparts.
  3. Nervous System: The nervous system is the control hub of an animal, collecting information from its environment (senses) and coordinating the animal's response. The nervous system includes sensory receptors, nerves, and in more complex vertebrates, a spinal cord and brain. The nervous system allows an animal to do everything from automatically controlling breathing and heartbeat to making memories and learning new things.
  4. Integumentary System: The integumentary system is the skin and other structures that make up or grow from the outer covering of animals, including fur, feathers, and claws. The main function of the integumentary system is to protect and separate the internal body of an animal from its external environment. Student learning focuses on scales, fur, feathers, and the exoskeleton of invertebrates.

Systems with which students may be familiar but are not covered in this module include: immune system (controls the body's response to illness and pathogens), circulatory system (transports nutrients and oxygen in blood throughout the body), excretory system (eliminates waste, such as in urine, from the body), reproductive system (allows animals to reproduce), and respiratory system (exchanges oxygen and carbon dioxide between the animal and its environment). (Inner Body)

Plant Structures

All vascular plants have leaves, stem, veins, and roots (non-vascular plants, such as moss and algae, are not discussed in this module). The parts of a plant can be thought of as a system because all parts must be present and working together in order for the plant to survive. The parts of the plants studied in this module include:

  1. Leaves: The leaves of a plant have stomata, which are similar to the skin of an animal. The stomata are where the plants absorb carbon dioxide and release oxygen as well as water vapor. Leaves with a large surface area release more water vapor, so a small or slender leaf is advantageous in an ecosystem with limited rainfall. Alternatively, leaves can have a waxy coating to help reduce water loss. Leaves are where food is produced through photosynthesis. In this module, photosynthesis may be named for students, but the process is not explained in depth. Spines are specialized leaves for protection.
  2. Stem: The stem of a plant provides structure and connects leaves to roots. The stem, as well as the roots and leaves, can also store food and water for the plant for later use.
  3. Veins: The veins of a plant run from the leaves through the stem and down to the roots. The veins carry water through tubes called xylem and food through tubes called phloem. These terms are not named for students, but the function of veins is discussed.
  4. Roots: The main jobs of the roots are to anchor the plant and to absorb water. There are two main categories of roots: fibrous and taproots. Students learn both of these terms. Fibrous roots are more like a blanket of roots and resemble the branches of a tree turned upside-down underground. Taproots are made up of one main root that has small root hairs branching off the main taproot.
  5. Flowers: The flower is a reproductive structure of the plant where pollen is produced. If the plant depends on insects to pollinate it, the flower will have a scent, petals, bright colors, and/or nectar and other features to attract insects. If the plant relies on wind pollination, the flowers will not have these adaptations.

Because grass thrives in the tundra, desert, and grasslands, students use it as a case study in this module. Grass is used to learn the basic structures and adaptations. Students also conduct an investigation comparing how grass and radish plants respond to a variety of environmental pressures in order to determine which plant survives, thrives, or dies in a given habitat. The environmental pressures are grazing, trampling, and drought--and in the grasslands, fire. The relationship between grazers (such as buffalo) and plants is complex. Students consider only one variable, a single grazing or trampling episode, and do not learn the effects of repeated trampling or grazing. Radishes and grasses are from each of the two main flowering plant families: monocots (grass) and dicots (radish). Grass has fibrous roots, an important adaptation for anchoring on windy plains and collecting water close to the surface in areas with little rainfall. Like many dicots, radish plants have taproots. Another difference between grass and radish plants is that grass has a growth tip that is much lower than a radish's. This is what allows grass to grow back when the stem or leaves are broken. In addition, when grass is broken, it stimulates rapid growth. A radish plant does not have that adaptation.

The differences between monocots and dicots can be observed first through their seeds. All seeds contain an embryo (baby plant), cotyledon (food), and seed coat (protection). Monocots have one cotyledon while dicots have two cotyledons. During the seed germination experiment, students observe the two cotyledons of the radish seed develop into the first two leaves whereas grass, with only one cotyledon, will produce only one leaf initially. In this experiment, geotropism is also observed. Geotropism is a function of the roots in which the roots always grow down toward the center of the earth because of gravity, no matter what direction the seed is placed.

For germination to occur, the seed must be under the appropriate conditions, including having enough water, the correct temperature, and space for growth.

Seeds are also adapted for survival through their various structures for dispersal. Seed dispersal occurs because the offspring plant has a better chance for survival if it is not competing with its parent plant for resources such as light, nutrients, and space. Specialized structures allow seeds to be dispersed by wind, water, animal "walk-by," or animal consumption:

  • Wind: Structures that are lightweight and designed to catch the wind
  • Water: Internal air pockets that allow the seed to float on water, away from the parent plant
  • Animal walk-by: Structures include Velcro(r)-type hooks that attach to an animal as it moves past the parent plant
  • Animal consumption: Seeds are inside a fruit that is consumed by an animal and then passed through its digestive system unharmed


Additional Resources

For more science background information:

For information on vendors:

Living organisms can be purchased at:

For more information on the NGSS Performance Expectations, including the evidence statements:

For more information on science instruction in the elementary classroom:

  • Engineering Is Elementary Video Snippets illustrate the teaching and learning processes that support hands-on engineering in the classroom.
  • National Research Council, Ready, Set SCIENCE! Putting Research to Work in K-8 Science Classrooms describes the kinds of learning experiences and instructional practices that are necessary for students to develop a deep understanding of science.
  • The Inquiry Project--Talk Science Primer provides guidance for developing a culture of productive talk in classrooms.
  • Tools for Ambitious Science Teaching provides a constantly evolving set of tools aimed at improving student participation and learning.
  • NGSS@NSTA provides NGSS curriculum planning resources as well as professional learning materials.
  • NGSS Resources contains a variety of materials to support implementation of NGSS, including links to the Evidence Statements that help clarify the standards.

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