Third Grade Integrated NGSS
Life Cycles, Growth and Development


Classifying arthropods and other little critters in Science Garden.

THIRD GRADE - arthropod classification

  •  Classifying different types of arthropods
  • Observing different little critters
  •  spider  
  • arthropod
  • insect

·         insect anatomy pdf  worksheet

·         insect book pdf

·         Insect data booklet

·         Scissors

·         glue

·         index cards


      ARTHROPODS (ppt)


Arthropods are bilaterally symmetrical and have jointed body segments with a pair of appendages attached to each body segment. The body is covered with a cuticle (thickened substance) which comes off ("molts") when the arthropod gets larger. There is no internal skeleton. Their circulatory system is very simple and they reproduce by laying eggs.  Many insects go through metamorphosis or physical changes.  So a butterfly is the adult insect but the caterpillar is one of the early stages and looks more like a "worm" than an insect.  Many arthropods like mosquitoes spend most of their life in an aquatic form before it metamorphoses into a flying insect. 

Identification of arthropods is not easy, because there are so many "creepy crawlies" out there. Below is  information that may help you group arthropods for your students. You may want to use other books or information on the internet to help identify the different arthropods. 

Spiders, scorpions, ticks, and horseshoe crabs belong to a group called the chelicerates. They have no antennae and the first pair of appendages are pincher-like. 

The arthropods called mandibulates are characterized by their head appendages and include most of the common  arthropods. We will be concentrating on the more common insect and crustacean groups.  A head (a), thorax (b), abdomen (c), wing cover or elytra (d), wing (e) and antennae (f)  are usually present.  Crustaceans, such as brine shrimp, are predominantly aquatic and have gills for respiration


1.    Use the Insect Anatomy Worksheet and have the students color the correct area.  Talk about a legend and how to use color to make the parts distinct.  For example, color the word “head” red and then color the head portion of the grasshopper red. 

2.    Insects are some of the most successful land organisms. Insects bite humans, irritate skin, and sometimes cause disease. The insect body is composed of a head, thorax, and on abdomen with 6 legs. The head has a pair of compound eyes. 

3.    Have students cut out the cards and assemble.  Punch a hole on the top and with yarn, tie them together to make a flip chart.  They can use this when they try to identify the species.

QUESTION:  How does the arthropod and other little critter population change through time?

Students shake the vegetation to find arthropods and other little critters.  If they do the project either weekly or bimonthly they should start seeing different arthropods.  This has several variables including time of the year, but also different plants will attract different arthropods.

PRIOR RESEARCH:  Do arthropods always look the same?  Which ones go through complete metamorphoses, and how do they look?  Maybe students can do a report on the bugs they predict they will see.

EXPERIMENTAL DESIGN:  Assign plants to team of students.  Each class should have someone do the same plant, maybe at different times of the week.  Best time would be spring time over a set amount of time.  Record temperature, moisture, wind in booklet. Lab booklet needs to include major type of organisms (that they will start in one of the docent labs) and record what they see.  Project should collect data in Oct through March, taking into account that during the rainy season you may not find any insects.



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