Lesson 2: Life Cycles
Jump To
- Big Ideas
- Essential Questions
- Content Outcomes Addressed
- Content Standards
- Background for Butterflies and the Monarch
- Vocabulary
- Concepts to Discover
- Pre- and Post-Assessment
- Misconceptions
- Investigation: Raising Monarchs
- Extensions
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Big Ideas
- Organisms reproduce, develop, have predictable life cycles, and pass on traits to their offspring.
- Organisms and their environment are interconnected.
- Changes—whether caused by nature or by humans—in one part of the system will affect other parts of the system.
Essential Questions
- How do organisms change as they go through their life cycles?
- How are plants and animals interdependent?
- How can change in one part of an ecosystem affect other parts of the ecosystem?
Content Outcomes Addressed
Students will be able to
- demonstrate knowledge of needs of living things by raising monarch butterflies.
- take responsibility for raising the monarch from eggs and/or caterpillars through butterfly stage by feeding them and maintaining their cages.
- observe, measure, chart, graph, record in drawings and writing, and interpret information.
- demonstrate knowledge of the monarch life cycle.
- note the interdependence of animals and plants.
- discuss hazards facing the monarch in captivity and in the wild.
Content Standards
NGSS:
- Disciplinary Core Ideas: ESS3.A (K-2), ESS3.B (3-5), ESS3.C (K-2) (3-5), LS1.A (3-5), LS1.B (3-5), LS1.C (K-2) (3-5), LS1.D (K-2) (3-5), LS2.A (K-2) (3-5) (6-8), LS2.B, (3-5), LS2.C (3-5), LS2.D (3-5), LS3.A (K-2) (3-5), LS3.B (3), LS4.B (3-5), LS4.C (3-5), LS4.D (K-2) (3-5)
- Science and Engineering Practices: 1-8
- Crosscutting Concepts: 1, 2, 3, 4, 5, 6, 7
CCSS: ELA/Literacy:
- Reading: RI.3.1, RI.3.2, RI.3.7, RI.4.7, RI.5.7
- Writing: W.3.7, W.3.8, W.4.7, W.4.8, W.5.7, W.5.8
- Speaking and Listening: SL.3.4
CCSS: Mathematics:
- Mathematical Practice: MP.2, MP.5
- Measurement & Data: 3.MD.B.3, 3.MD.B.4, 5.MD.A.1
National Geography Standards:
1, 2, 4, 8
Background for Butterflies and the Monarch
Raising butterflies in the classroom is truly an amazing experience for students and teachers alike. Students learn to take care of a living organism as well as observe the awe-inspiring development of and metamorphosis in the butterfly life cycle. If your school is located in an area where monarchs visit, whether in the fall or the spring, you and your students can collect the eggs and/or caterpillars, bring them inside, raise them with care, and you will be treated to a special natural wonder. If you are not able to find milkweed in your area, use this lesson plan as a model for raising a different organism that you are able to find in your local environment. If you have milkweed in your area but cannot find monarch eggs or caterpillars, contact Monarch Watch (monarchwatch.com) for information on reliable sources for obtaining monarch eggs and caterpillars.
Butterflies belong to a group of animals known as insects. Insects have been on Earth for about 400 million years. There are more different species of insects than any other group of animals! Insects have six legs and a segmented body made up of three main parts: head, thorax, and abdomen. The thorax consists of three segments behind the head and is where the wings and legs are attached. Insects have an external skeleton (exoskeleton). Insects develop from egg to adult in one of two ways. Some go through complete metamorphosis, in which the adult is very different from the juvenile; others go through incomplete metamorphosis, in which the adult looks like the juvenile, except it has developed wings. Butterflies undergo complete metamorphosis. All butterflies have four wings as adults: two forewings and two hindwings.
Many butterflies feed on flowers, sucking nectar with their long proboscis. In addition, many caterpillars feed on plants, chewing their leaves. This trait has led to the interdependence of butterflies and flowering plants. Many insects feed on flowers (pollen or nectar) and many flowering plants rely on insects for pollination (bees, wasps, ants, flies, beetles, moths, and butterflies). The milkweed plant, host to the monarch larva and butterfly, is also host to a multitude of different species of insects. Some insects are attracted to the nectar and pollen of milkweed flowers, while others feed on the leaves, seeds, stems, or roots.
Butterflies undergo complete metamorphosis, changing from a larva to a very different-looking adult. The development of a butterfly from egg to adult can take anywhere from three weeks to several years to complete, usually depending on the climate. A shorter development cycle occurs in warmer climates. Monarchs take about one month to go from egg to adult. They develop from an egg to a larva, or caterpillar (the stage in which they eat plenty of milkweed), to a pupa, or chrysalis (the resting stage), and then emerge as an adult. Adult monarchs live for about two to six weeks in the summer months, but the generation that travels to Mexico lives through the winter, for a total of up to nine months.
Like all organisms, monarchs have a range of temperature and other conditions in which they grow best. Dry conditions will hinder the hatching of the eggs and the development of the milkweed, the only plant that the monarch caterpillar eats, and can reduce flower nectar that the adults eat. Very hot weather and very cold weather can kill the monarchs in all stages. Herbicides and insecticides can also kill monarchs (Source: Monarch Teacher Network. Journeys: Learning Activities from the Monarch Teacher Network. NJ: Educational Information & Resource Center, Global Connections, 2006.).
Vocabulary
- exoskeleton: an external skeleton
- proboscis: a long, tube-shaped body part (as the sucking organ of a butterfly) in the mouth region of an invertebrate
- interdependence: depending on one another
- metamorphosis: the process of basic and usually rather sudden change in the form and habits of some animals during transformation from an immature stage (such as a tadpole or a caterpillar) to an adult stage (such as a frog or a butterfly)
- larva: a young, wingless, often wormlike form (such as a grub or caterpillar) that hatches from the eggs of many insects
- pupa:a stage of an insect (such as a bee, moth, or beetle) having complete metamorphosis that occurs as it changes from a larva to an adult, usually inside a cocoon or a case
- chrysalis: the pupa of a butterfly or moth; the hardened outer layer of such a pupa
- herbicide: a chemical substance used to destroy or stop plant growth
- insecticide: a chemical used to kill insects
Concepts to Discover
- Different species of animals grow and develop in different ways.
- Animals need the right conditions to stay alive.
- Animals and plants depend on each other for survival.
Pre- and Post-Assessment
What do we already know? Students predict, draw, and/or write their ideas about these questions:
- What is a life cycle?
- How is the life cycle of the butterfly like a human’s life cycle?
- How do plants need animals to survive, and how do animals need plants to survive?
Student responses to these pre-assessment questions will reveal common misconceptions and will indicate their level of understanding. At the end of the unit, check again for understanding to see what has been learned.
Misconceptions
- Students think that caterpillars are worms.
- Students believe that butterflies are simply caterpillars with wings.
Investigation: Raising Monarchs
Materials
- Worksheet 1: Monarch Life Cycle Log
- Worksheet 2: Life Cycle Photographs
- milkweed plant
- monarch eggs or caterpillars
- cage materials (e.g. deli containers or orange juice cartons with nylon knee-highs, metal lampshade frame with cheesecloth, tomato cage with tulle fabric and plastic tray or newspaper, glass aquarium or jar with screen, empty plastic water bottle)
- pencils, colored pencils
- hand lenses and/or microscopes
Focus Questions
- Can you give us an example of the life cycle of an animal you know?
- What do all animals need in order to survive?
- Have you ever taken care of an animal? What did you have to do to keep the animal alive?
Procedure
- Search fields for milkweed and monarch eggs and caterpillars. Before beginning a unit on raising monarch butterflies, become familiar with the habitats near you. Look for a good supply of milkweed (refer to the photograph in Worksheet 2). Milkweed usually grows in fields in sunny locations. If you have milkweed, look on the undersides of the leaves for tiny white eggs or tiny caterpillars. If you find some, you will be ready to raise them in the classroom.
- Make observations and keep good records. Throughout its life cycle, students observe (using eyes, hand lenses, and/or microscopes) and record by drawing and writing about the monarch’s appearance and behavior. Students will use Worksheet 1 to keep track of the monarch’s development.
- Make a home for the eggs and caterpillars. You and your students can make a home for the eggs or caterpillars by using a container with holes to let in air (see Worksheet 2). The container can be a deli container with holes poked in the top, an orange juice carton with “windows” cut out on the sides and covered with a nylon knee high, a lampshade frame (without the shade on it) wrapped with cheesecloth, an upside-down tomato cage with tulle fabric wrapped around it and a plastic tray or newspaper for the bottom, or a glass aquarium or jar with a screen or some mesh placed on top. If you start with a small container, try to give the monarch a larger place to live as it gets bigger.
- Collect eggs and caterpillars in the wild. Cut the milkweed stalks and leaves that the eggs and caterpillars are on. Caution! Milkweed is poisonous to eat, so it is important for everyone in the class to wash their hands after they handle milkweed.
- Care for the eggs and caterpillars. Place the stalks of milkweed in a plastic water bottle filled with water. The eggs and caterpillars should be on the milkweed. Put the bottle and milkweed into the cage that you and your students built. If there is not enough space for the whole stalk, cut up fresh milkweed into small pieces each day. Replace the milkweed when it begins to look old (dry, rotting, etc). Be sure to keep the cage clean.
- Care for the chrysalis. After 1 to 2 weeks, the caterpillar will try to climb up somewhere high. Then it will attach itself to the top of the cage and hang for a day. Then, it will quickly turn into a beautiful, jade green chrysalis. Consider yourselves lucky if you and your students see this first change. It does not need food now, as this is the resting stage.
- Care for the butterfly. In 2 weeks, the chrysalis will turn clear, exposing the black and orange wings of the butterfly. Keep watching, and you and your class might see the monarch emerge from its chrysalis. Again, consider yourselves lucky if you get to see its final metamorphosis. Let the butterfly dry its wings for a day. Feed it with a mixture of 1 teaspoon of honey to 1 cup of boiled water that has cooled. If you put the mixture on your finger and gently hold the butterfly on your hand, it might extend its long proboscis and sip some of the honey-water from your finger!
- Release the butterfly. On a warm, sunny day, release the butterfly. You and your students will at one time be sad and happy to say good-bye! If it is in the spring or summer, this butterfly will stay local. If it is in the fall, your monarch will probably head south to begin its long migratory journey to Florida or Mexico, an amazing feat for such a tiny animal!
- Discuss the hazards the monarchs face both in captivity and in the wild. As you were raising the monarchs in the classroom, perhaps some of them died. Some eggs may not have hatched. One caterpillar may have escaped. Someone may have stepped on one. The milkweed may have gotten moldy. The caterpillars may have contracted a virus. In the wild, monarchs get eaten by predators, their milkweed fields may have disappeared, their roosting sites (trees they rest in overnight) may have disappeared, the temperature may have gotten too low or too hot, the humidity may have gotten too low, herbicides may have killed the milkweed or insecticides may have killed them. When the students raise monarchs in the classroom, they realize the responsibility they have to keep them safe and alive while in their care, and they begin to understand how changes due to environmental and human factors can affect their survival in the wild.
Extensions
- Raise a swallowtail butterfly. A common butterfly that you will see is the swallowtail. The female lays her eggs on parsley, dill, carrot tops, fennel, paw paw tree, citrus tree, prickly ash tree, Dutchman’s pipevine, tulip poplar, wild cherry tree, spicebush, and sassafras tree. If you have any of these plants at your home or school, take a look on the tops and bottoms of the leaves. If you find eggs or caterpillars, take them inside and raise them in a cage as you did the monarch. Be sure to feed them the plant that you found them on. You will be rewarded with a beautiful swallowtail butterfly. If you find the caterpillars in the spring, the cycle will be a couple of weeks. If you find them in the fall, they could emerge as butterflies in a couple of weeks, but if it is late in the fall, the swallowtail might overwinter in its chrysalis. Put the cage with the chrysalis in a garage or similar cold place. When spring begins, check the cage each day for a butterfly!
- Create butterfly cards. Add cards for the class collection. Include local caterpillars and butterflies and their hosts (plants that the caterpillars eat) and nectar plants (plants that provide nectar to butterflies).
- Start a butterfly garden. If you plant milkweed plants (host plants) and native butterfly-attracting plants (nectar plants), then the butterflies will come to you! Not only will the butterflies lay eggs, but you and your students also will have the unique opportunity of seeing first-hand how insects and plants are interdependent.
- Follow the monarch butterfly during its migration south in the fall and north in the spring. Join Monarch North (www.learner.org/jnorth/), a citizen science website that lets students track the monarch butterfly to and from Mexico. Students report and share their own observations of migrating butterflies using real-time migration maps.
- Raise a painted lady butterfly if an urban environment prevents you from raising the monarch or swallowtail. Resources are available through Carolina Biological Supply Company at www.carolina.com/.