Lesson Plan

Life Cycles

Frog.

NPS photo by Lee Ferguson

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Grade Level:
First Grade
Subject:
Biology: Animals, Biology: Plants, Ecology
Duration:
30 Minutes
Setting:
outdoors
National/State Standards:
Utah Integrated Core Curriculum Topic, Standard Four: Students will gain an understanding of Life Science through the study of changes in organisms over time and the nature of living things.
Keywords:
Life cycle, metamorphosis, seasonal changes, Butterflies, frogs, insects, galls

Overview

Students explore plant changes by performing a play depicting the life cycle of a wildflower through the seasons. They explore life cycles of frogs and toads, along the way discovering the difference between them. Students learn about insect metamorphosis, focusing on moths and butterflies, and discover the surprising world of insect galls.

Objective(s)

PRE-TRIP ACTIVITY
Wow! Things Change

a. Name at least one example of changes that plants go through during their life cycles.
b. Name one example of a change that animals go through during their life cycles.
c. Identify the purpose of seeds in the plant life cycle.


STATION #1
Season Suite

a. Describe the parts of a wildflower life cycle.
b. Name the four seasons, and describe their influence on a wildflower life cycle.


STATION #2
Swim, Swim and Hop a Lot

a. Describe the stages of the amphibian life cycle.
b. Describe why frogs sing in the night.


STATION #3
Flutter By

a. Describe the life cycle of a butterfly.
b. Name two differences between butterflies and moths.


STATION #4
What Gall!

a. Identify galls and see differences between different types of galls.
b. Describe the different stages of complete metamorphosis.


POST-TRIP ACTIVITY
a. Describe the life cycle of a flower.
b. Name the four insect stages of complete metamorphosis.
c. Describe the cycle stages of frogs

Background

Plants sprout from seeds, grow, and produce flowers, which, if pollinated, produce more seeds. Plants need sun, soil, and water in order to make their own food and grow. Insects, hummingbirds, and bats inadvertently pollinate flowers while seeking nectar. Some plants, such as coniferous trees, rely on wind to distribute pollen.

Insects are an extremely diverse group of animals. They have exoskeletons, six legs, and three body parts. Although most insects have two pairs of wings, flies have only one pair and some have no wings at all. Wings are only found in adult insects. Most insects have a pair of some type of antennae. These and the tiny hairs sticking out of insect exoskeletons help the insects to feel, smell, and in some cases, hear. A simple heart pumps insect blood through its body cavities, distributing dissolved food and removing wastes. Because the blood does not carry oxygen, it is not red.

Insects undergo either complete or incomplete metamorphosis throughout their life cycles. Insects going through incomplete metamorphosis have three stages: egg, nymph, and adult. Nymphs often look like miniature adults, such as in grasshoppers, cockroaches, and aphids. However, some nymphs live in the water and look different than the adults. Examples include damselflies, dragonflies, and mayflies. Insects going through complete metamorphosis have four life cycle stages: egg, larva, pupa, and adult. Examples are butterflies, moths, flies, ants, wasps, and beetles. Larvae look completely different than their adult forms. Some larvae are aquatic and others are land-dwellers. A cocoon is a pupal case for a moth. A chrysalis is a pupal case for a butterfly.

Butterflies and moths experience complete metamorphosis. All of the parts of a butterfly are adapted for survival. The abdomen of thebutterfly is large when it first emerges from its chrysalis. It becomes smaller when it starts pumping fluids into its wings. In all its stages the butterfly breathes through tiny holes called spiracles. Wings are covered with millions of colored scales that camouflage the butterfly. The butterfly’s proboscis (i.e. tongue) is used to sip nectar from flowers. The butterfly’s compound eyes are made up of thousands of tiny lenses that help it see in all directions at once. Moths have different features than butterflies. Both butterflies and moths have both a fore and an aft wing on each side of their bodies. Among most moths, the aftwing is attached to the forewing by a hook, called a frenulum. Butterflies lack a frenulum and only hook their wings together in flight. Moths are nocturnal; butterflies are diurnal. Most moths rest with their wings flat; most butterflies rest with their wings upright. Moths have feathered antennae; butterflies have straight plain antennae. While a moth’s abdomen is fat, the butterfly’s is thin. Moths form cocoons; butterflies form chrysalises.

Galls are temporary homes for some insects. They form when an insect chews on and injects a chemical into a plant, causing a swelling. Each species of gall-making insect has its own special species of plant that it must choose, or its specific gall will not form. The variety of sizes and shapes that galls take is impressive. Oak apples, bumps and lumps on hackberries, swellings on cottonwoods, cottony balls on rabbitbrush, and cone-like growths on Utah juniper are all types of galls, each created by one insect species.

Each type of gall has its own story, but many house and feed the larva and pupa of a certain insect. The larva is commonly legless and blind, as its stage of the life cycle is contained within its food source, the gall’s interior. Most gall-forming insects are small flies or wasps, but certain aphids, moths, beetles, and psyllids are also gall-formers.

Amphibians are animals that lead two lives. When they are young, amphibians are specifically adapted to living in the water. They use gills to breathe and use their tails to help them swim. As adults they walk or hop on land and use lungs to breathe. In the spring, frogs and toads lay a mass of eggs and attach this mass to rocks or sticks. The hatched tadpoles eat mostly bacteria and algae. The length of time an amphibian spends in this larval stage depends on the species. A bullfrog can take over a year to undergo metamorphosis; a spadefoot toad can change in less than two weeks. Eventually, however, most amphibians grow legs, lose their tail, grow lungs, and lose their gills. They begin to eat insects rather than plants and spend their time on land. Frogs and toads are not scientific distinctions. Rather, they are common terms used to describe either adult amphibians that have smooth skin and spend most of their time near water (frogs) or fatter adults with bumpy skin that spend most of their time away from water (toads). Other amphibians include salamanders and caecilians.

Procedure

Extensions

STATION #1
Season Suite

Have students interview each other to discover the details of the wildflower cycle and the effect seasons have on the cycle. Coordinate students in creating a classroom wildflower cycle display using construction paper or other materials.


STATION #4
What Gall!

In small groups, have students create soil that they think would both filter and hold water as well as wetlands soil does. Have each student in a group bring an element (i.e. dead plants, sand, and mud) to mix together. Compare a jug test on the mixture to the wetlands soil jug test. Discuss results and what they could add or take out to make the soil more like wetlands soil.


POST-TRIP ACTIVITY
Cycles, Cycles, Cycles

Have students return to their desk and split the class in half. Tell one side that they are tadpoles and the other side that they are adult frogs. When you hold up a description of a body part or environment that their side uses (i.e. a long tail = tadpoles, dry land = adult ) everyone on that side should raise their hand. Vary between pictures and descriptions for tadpoles, adult frogs and examples that neither has/needs.

Additional Resources

Caduto, M. & Bruchac, J. (1988). Keepers of the earth: Native american stories and environmental activities for children. Golden, CO: Fulcrum.

Carle, E. (1987). The tiny seed. New York, NY: Scholastic.

Carle, E. (1969). The very hungry caterpillar. New York, NY: Putnum.

Clover Kids. (n.d.). Beautiful butterflies. retrieved July 29, 2003 from www.extension.iastate.edu/4h/clover/butterfliesck

Earth’s Birthday (n.d.) retrieved July 29, 2003 from www.earthsbirthday.org/butterflies.

Emmel, T. C. (1975). Butterflies. New York, NY: Alfred A. Knopf.

Heller, R. (1983). The reason for a flower. New York, NY: Grosset & Dunlap.

Incredible insects. (1989). Ranger Rick’s NatureScope. Washington, DC: National Wildlife Federation.

Let’s hear it for herps. (1987). Ranger Rick’s NatureScope. Washington, DC: National Wildlife Federation.

Lingelbach, J. (Ed.). (1986). Hands-on-nature: Information and activities for exploring the environment with children. Woodstock, VT: Vermont Institute of Natural Science.

Mathewson, R. (1987). Reptiles and amphibians. Los Angeles, CA: Price Stern Sloan, Inc.

Morreale, S.J., Kransy, M.E., & Schneider, R. L. (2001). Hands on herpetology: Exploring ecology and conservation. Arlington, VA: NSTA Press.

Santore, C. (Illus.). (1988). Aesop’s fables. New York: Jelly Bean Press.

Tweit, S. J. (1992). The great southwest nature factbook. Bothell, WA: Alaska Northwest Books.

Willis, J. (2000). What did I look like when I was a baby? New York: Scholastic.

Williams, D. (2000). A naturalist’s guide to canyon country. Helena, MT: Falcon Publishing.

Last updated: November 15, 2017