seegongsik
Grade 2 (age 7-8)

grade 2 World of Insects

Insects are the small animals we see most often around us. Ants, butterflies and dragonflies look different, but every insect's body has three parts, a head, a thorax and an abdomen, with six legs attached to the thorax. Insects each have work to do in nature, such as carrying pollen so that fruit can form, or breaking down dead plants and animals. Choose an insect in the picture to see where its three body parts, legs, antennae and wings are.

Looking at insects

Butterfly

What insects have in common

Classification

Insect Features
🔍 What all insects share
①The body has three parts: head, thorax and abdomen
②There are 6 legs (3 pairs), all attached to the thorax
③A pair of antennae on the head smell and feel the surroundings
④Insects with wings have them on the thorax too, 2 or 4 of them; the ant in the picture is a wingless worker ant

How insects grow

🦋 How a butterfly grows (complete metamorphosis)
①It grows in the order egg → larva (caterpillar) → pupa → adult (butterfly)
②The caterpillar eats leaves and sheds its skin several times as it grows
③Inside the pupa its body changes completely and wings form
④A life cycle with a pupa stage like this is called complete metamorphosis
🦗 How a grasshopper grows (incomplete metamorphosis)
①It grows in the order egg → nymph → adult
②There is no pupa stage
③The young look like the adults and grow wings as they shed their skin

Summary

🎯 Insects in short
①Insect: three body parts (head, thorax, abdomen) and 6 legs
②Spiders (8 legs), centipedes (very many legs) and snails (no legs) are not insects
③A life cycle with a pupa, like the butterfly's, is complete metamorphosis; one without, like the grasshopper's, is incomplete metamorphosis
④Insects are the group of animals with the most kinds on Earth

Examples and Unit Test

Example 1
How many parts does an insect's body have, and how many legs?
1
An insect's body has three parts: head, thorax and abdomen.
2
The legs come from the thorax, 6 in all (3 pairs).
▸ Body: head, thorax, abdomen / 6 legs
Whichever insect you choose in the picture, the three body parts and 6 legs stay the same.
Example 2
Starting from an egg, in what order does a butterfly grow into an adult?
1
A caterpillar hatches from the egg and grows by eating leaves.
2
The caterpillar becomes a pupa, and a butterfly comes out of the pupa.
▸ Egg → caterpillar → pupa → butterfly
A life cycle with a pupa stage, like the butterfly's, is called complete metamorphosis.
Unit Test
Which of these is not an insect?
①Butterfly
②Ant
③Spider
④Dragonfly
⑤Ladybug
▸ ③ Spider
1
An insect's body has three parts (head, thorax, abdomen) and 6 legs.
2
A spider has 8 legs and a body in two parts, so it is not an insect. All the others are insects.
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