STEM Club: Simple Invertebrates - Eva Varga

October 24, 201324

I love invertebrates!  I spent a summer at the Oregon Institute of Marine Biology some years ago immersing myself in invertebrate zoology and I learned so much.  I am now teaching STEM Club about inverts but sadly only have two weeks in which to impart as much as I can.

sponges, worms, & cnidariaThere are more than one million known kinds of invertebrates! Invertebrates are animals that do NOT have a backbone. Every invertebrate is classified in a large group called a phylum.  There are 27 animal phyla. The phyla groups are then subdivided into classes.  In STEM Club, we simplified the invertebrate animal phyla into 6 groups: SpongesWorms, and Cnidaria (Animals with Stinging Cells), Enchinodermata (Animals with Spiny Skin), Mollusca (Animals with Soft Bodies), and Arthropoda (Animals with Jointed Legs and an Exoskeleton).

To begin, there are several vocabulary words regarding symmetry (the form or the arrangement of  an animal’s body) that need to be defined:


  • asymmetry – a body having no definite body shape or form (i.e. no symmetry)
  • bilateral symmetry – a body having both sides equal; right and left halves are the same (“same on both sides”)
  • radial symmetry – a body which spreads or branches out in all directions from a common center (generally contains the ‘mouth’ opening)

charting inverts

Once we had a basic understanding of these terms, we proceeded to complete a chart identifying the invertebrate groups, Charting the Animal Kingdom: The Invertebrates.  As I described the key characteristics for each group of invertebrates, the kids were instructed to fill out their chart. In addition, they were encouraged to list a few representative examples and to make a quick illustration for each.

~ ~ ~


  • Many celled organism (2 cell layers w/ jellylike substance between)
  • Simple, asymmetrical porous bodies (covered with holes)
  • Tubular shaped bodies; no head, mouth, tissues or organs
  • Chambers or holes lined with special cells w/ whip-like flagella
  • Flagella create current that pulls water into sponge and send it out again through larger exit openings
  • Sessile (encrusting – found in intertidal, close to rocky surface; or erect – found deeper/quieter waters, coral reefs)
  • Body composed of calcareous or siliceous spicules (variety of forms, important for identification and classification of species)

Upon completing the sections for sponges, I handed out a number of sponge specimens from my Cabinet of Curiosities. As they observed the sample closely, I discussed how the flagella work to bring water and food into the body cavity.  I also shared diagrams of the tiny spicules.


  • Three main phyla – segmented worms, flatworms, and roundworms
  • All worms are bilaterally symmetrical
  • Segmented worms include earthworms, leeches, and tube worms
  • Segmented worms have paired setae bundles (stiff hairs) on each segment, five hearts, and are hermaphroditic
  • Segmented worms can be burrowers, tube dwelling, planktonic, few parasitic
  • Flatworms have eye spots, most are parasitic, and have some nerves
  • Some flatworms, like the planarian, can regenerate
  • Roundworms and segmented worms have two body openings (food and waste)
  • Some roundworms are parasitic and some have a digestive system

To engage the kids and bring these concepts to life, I brought in live earthworms that they observed and sketched in their notebooks.  In addition, I had a microscope set up with an earthworm cross-section and a planarian.  When their illustrations were complete, I walked them through the labeling of the major parts we observed.


  • Two main body types – medusa and polyp
  • Some exhibit both body types depending on stage of life cycle
  • Radial symmetry
  • Simple bodies with one body opening (food and waste both) surrounded by tentacles
  • Tentacles lined with special cells called nematocysts
  • Includes jellyfish, anemones, and coral

As Cnidaria have soft bodies, they don’t preserve well (except in fluids like Formaldehyde – which I do not have in my Cabinet of Curiosities).   I thereby passed around the calcareous or limestone remains of a variety of coral samples I have collected over the years.  As they observed the sample, I explained that a coral “head” is a colony of myriad genetically identical polyps. Each polyp is typically only a few millimeters in diameter and a few centimeters in length. A set of tentacles surround a central mouth opening and an exoskeleton is excreted near the base. Over many generations, the colony thus creates a large skeleton or ‘house’ that is characteristic of the species.  I also shared numerous photos of live coral that I have pulled from numerous magazines.


invertebrate foldable

In addition to the chart shown above, I’ve created a hexagonal accordion fold mini-book with which the kids can investigate an invertebrate of their choice. The download link for both the Invertebrate Investigation foldable (shown here) and Charting the Animal Kingdom: The Invertebrates notebooking pages (shown above) are available to my newsletter subscribers. Please subscribe to my newsletter for access to these exclusive subscriber only resources.

zoologyThese free printables are wonderful additions to the Amazing Animals curriculum unit I have written to introduce middle level students to zoology.  This 10-week unit is full of inquiry-based activities and lesson plans fully outlined for you.


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  • Sunni

    January 28, 2014 at 5:36 pm

    Hi – thanks so much for all the freebies on this site – I would love to have these foldables if you are still giving them away! 🙂

    • Eva Varga

      January 28, 2014 at 7:52 pm

      Most certainly! I’ve sent you an email. 🙂

  • Chrystie Limes

    February 9, 2014 at 5:25 am

    I’d like to have the invertebrates freebie too. I know that it will be very beneficial in teaching invertebrates this month.

    • Eva Varga

      February 10, 2014 at 8:23 am

      I’ve sent you an email, Chrystie! 🙂

  • Sharon Landgraf

    March 3, 2014 at 1:31 pm

    Ideas look great! Would enjoy using your foldable with my students.

    • Eva Varga

      March 4, 2014 at 5:50 am

      Hi Sharon! Thank you so much! I’ve sent you an email with the download links. Enjoy!

  • Amy

    March 23, 2014 at 6:05 pm

    Hi. I would love to use your downloads for our homeschool zoology! Thanks for all the info on your site. Additionally, do you think that your insect class would work for a 7 year-old who is very into insects?

    • Eva Varga

      March 24, 2014 at 7:16 am

      You are so welcome! Science is my passion and it is a joy to share it with others. I am not currently offering the insect class live, however, the lessons and materials that I used are available as an eBook in my store. I feel strongly that the material is adaptable to younger students, particularly those with a strong interest in entomology (study of insects). There is a lesson on scientific classification and though it may be a little difficult to grasp all the Latin order names, it would provide a good foundation on which to build.

  • Anna McJunkin

    March 24, 2014 at 1:37 pm

    Hello! I would love to obtain these printables (including the fodable) if possible! Thank you

    • Eva Varga

      March 24, 2014 at 3:54 pm

      The fifth and final request! I’ve sent you a email, Anna. Enjoy! 🙂

  • Cindy Brewer

    January 6, 2015 at 1:19 pm

    I wish I would have found this site sooner! I am taking on a friend’s son who is in 3rd grade (sort of) and has ADD, Dyslexia and Apraxia. Do you have any suggestions about what might work well with him in a notebook?

    • Eva Varga

      January 9, 2015 at 5:13 am

      In my experience, notebooking lends itself well to students with ADD and Dyslexia. However, I have no personal experience with Apraxia. The positives of interactive notebooks is that they provide students with a manipulative – little pages to turn or unfold. The writing space is small and thereby not overwhelming and students are encouraged to incorporate little pictures or sketches to help them remember the meaning of the word. Rather than writing out extensive lists of vocabulary, the text is short and appealing to the eye.

  • Alina

    February 2, 2015 at 8:53 am

    Looking forward to it!

  • karen byassee

    April 24, 2015 at 6:36 pm

    Your material is fabulous! Thank you so much.

  • Robin Williams

    May 14, 2015 at 12:02 pm

    Just found your site. Looks great for teaching an into to invertebrates. I would love your download for the foldable and chart. Thanks so much for taking the time to make this available to others. Sharing is great!!

  • Lacey

    July 7, 2015 at 9:01 am

    Would love the foldable!

    • Deanna

      July 15, 2015 at 7:51 am

      If you’re still e-mailing them out…I would love this foldable and the chart. Thanks so much!

  • A.J.

    July 15, 2015 at 5:01 am

    Hello, I’d love to have the free foldables if you’re still offering them. Thank You for sharing!

  • Joy Briggs

    July 15, 2015 at 6:10 am

    I love this information! It will make a wonderful addition to our invertebrate lessons this year. I would love to receive those files and I’ve included my email …. Thank you so much for sharing!

  • Diane Wheless

    July 15, 2015 at 7:29 am

    I would love to have the foldable. I have only just found your site TODAY! Thank you so much, you have tons of helpful info here!

  • James Walters

    July 15, 2015 at 10:07 pm

    Awesome… want to use them for a couple of Boy Scouts working on the Insect Study merit badge. May I have the links as well? It says I am subscribed, but I don’t see any messages… time to check the spam filters!

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