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    Topic
    How do living things change?How do living things change?
    Arthropods
    by Martin Reed
    1 Living things change over time. They change or evolve in order to adapt
    to changes in their environment. If they don’t adapt, they may not survive.
    Arthropods are one example of a species that has evolved over time.
    2 Arthropods are invertebrate animals. They don’t have a spinal column, but
    many have an exoskeleton, or shell. Their bodies are bilaterally symmetrical and
    segmented. They also have many pairs of jointed limbs. The five main groups of
    arthropods are insects, spiders, scorpions, centipedes and crustaceans.
    3 Arthropods have existed and evolved for more than 500 million years.
    Fossils from the Cambrian period prove the earliest existence of arthropods.
    Examples of ancestors of different branches of the arthropod family from this
    period are trilobites, merostomes (ancient scorpions) and crustaceans. Spiders,
    or arachnids, first appeared during the Devonian Period, which is also known
    as the “Age of Fishes.” Zoologists found fossils of the first centipedes, millipedes
    and other insects later on, during the Carboniferous period.
    4 We can still see arthropods everywhere. There are millions of species and
    subspecies living in water and on land in different climates. They can be very
    small (0.25mm) or as big as 3.8 meters long. They are the lowest life forms on
    the food chain, but they have survived and evolved successfully. Their incredible
    ability to adapt is the reason they have survived for millions of years.
    Cambrian Period
    (543-490 million years ago)
    Crustaceans and Scorpions Centipedes and InsectsSpiders
    Devonian Period
    (416-358 million years ago)
    Carboniferous Period
    (358-299 million years ago)
    Sources:
    “Understanding Evolution” http://evolution.berkeley.edu/evolibrary/article/arthropods_toc_01 Accessed August 22, 2016.
    “Arthropod: Evolution and Paleontology” https://www.britannica.com/animal/arthropod/Evolution-and-paleontology
    48
    1 Read the text. Answer the questions.
    1
    What is the purpose of the text?
    2
    Who did the author write the text for?
    3
    Where can this text be published?
    4
    What is the text about?
    2 Match the words with the definitions or synonyms.
    1
    arthropod
    a
    shell
    2
    bilaterally symmetrical
    b
    arms and legs
    3
    exoskeleton
    c
    with two equal halves
    4
    invertebrate
    d
    no vertebrae
    5
    limbs
    e
    divided
    6
    segmented
    f
    invertebrate creature
    3 Look at the text. Write the number of the paragraph that contains this information.
    1
    definition of an arthropod
    2
    introduction to the topic
    3
    when different arthropods first appeared
    4
    characteristics of an arthropod
    5
    size of modern arthropods
    4 Using a Timeline Look at the timeline. Complete the table.
    5 Punctuation
    Find an example of each way a comma
    is used in the text.
    Write them here.
    1
    to separate words in a list
    2
    to combine two sentences
    3
    to separate extra information from the main sentence
    Using a Timeline
    A timeline is a graphic
    representation of
    events in chronological
    order. Writers use
    them to provide visual
    support to written text.
    Punctuation
    Commas are used
    three ways in this text:
    to separate words
    in a list, to combine
    two sentences and
    to separate extra
    information from the
    main sentence.
    Time period Fossils of Arthropods
    Cambrian Period
    Devonian Period
    Carboniferous Period
    49Topic 6
    1 Answer the questions.
    1
    What will be the purpose of your text?
    2
    Who are you writing the text for?
    3
    Where will you publish your text?
    4
    What sources could you reference?
    2 Think about human evolution. Do some research. Brainstorm and write the words you might use.
    3 Write some ideas for your text.
    Periods of Time Descriptions of Time Periods
    Names of Human Ancestors Descriptions of Human Ancestors
    50 Topic 6
    4 Complete the table for human evolution.
    5 Complete the table for your research paper.
    6 Write a topic sentence for each section in activity 5.
    1
    2
    3
    4
    Age Time (years)
    Characteristics of the Period
    Evidence of Human / Humanoid Life
    Paleolithic
    Mesolithic
    Neolithic
    Introduction
    Definition of
    Species
    Main Ideas
    Conclusion
    Evolution of Human Beings
    51Topic 6
    1 Write your text. Include a timeline.
    My Classmate’s Checklist
    2 Exchange books with a classmate. Read the sentences. Mark (✓) Ye s or No.
    1
    The text is about human evolution.
    2
    There is an introduction and a conclusion.
    3
    Scientific words are defined.
    4
    The main ideas are expressed clearly.
    5
    There is a timeline.
    Yes No
    Yes No
    Yes No
    Yes No
    Yes No
    My First Draft
    52 Topic 6
    3 Rewrite your text. Include a timeline.
    My Classmate’s Checklist
    4 Exchange books with a classmate. Read the sentences. Mark (✓) Ye s or No.
    1
    The text is about human evolution.
    2
    The text has an introduction, main ideas and a conclusion.
    3
    Scientific words are defined.
    4
    There is a timeline.
    5
    Commas are used correctly.
    Yes No
    Yes No
    Yes No
    Yes No
    Yes No
    My Second Draft
    53Topic 6
    54 Topic 6
    55Topic 6