activity 21 Meet the Larvae BROWARD COUNTY ELEMENTARY SCIENCE BENCHMARK PLAN Grade K Quarter 3 Activity 21 SC.F.1.1.1 The student knows the basic needs of all living things SC.H.1.1.1 The student knows that in order to learn, it is important to observe the same things often and compare them. SC.H.1.1.3 The student knows that in doing science, it is often helpful to work with a team and to share findings with others. ACTIVITY ASSESSMENT OPPORTUNITIES The following suggestions are intended to help identify major concepts covered in the activity that may need extra reinforcement. The goal is to provide opportunities to assess student progress without creating the need for a separate, formal assessment session (or activity) for each of the 40 hands-on activities at your grade. 1. Ask, What are some things butterfly larvae need to stay alive? (They need food, air, water, and room to move.) Then ask, Which of those four things can we control in the classroom? (We can control all of them. We need to make sure they have enough food, water, and air. We also need to give them room to move.) 2. Use the Activity Sheet(s) to assess student understanding of the major concepts in the activity. In addition to the above assessment suggestions, the questions in bold and tasks that students perform throughout the activity provide opportunities to identify areas that may require additional review before proceeding further with the activity. broward county hands-on science Quarter 3 213
214 activity 21 Meet the Larvae
activity 21 Meet the Larvae OBJECTIVES Students discuss how to care for living things appropriately, and are introduced to butterfly larvae. The students discuss how to treat living things set up containers with larvae food make initial observations of the larvae SCHEDULE About 40 minutes VOCABULARY larva larvae MATERIALS For each student 1 Activity Sheet 21 1 magnifier For each team of two 1 container, 1-oz, with lid For the class 16 butterfly larvae, with food 1 cont butterfly larvae food, extra 4 markers* 1 pipe cleaner, 30 cm long 1 ruler, metric* 4 spoons, plastic 1 roll tape, masking *provided by the teacher PREPARATION 1 2 3 4 Make a copy of Activity Sheet 21 for each student. Set up a distribution station with the container of extra butterfly food and four spoons. (Wash your hands before handling the food or spoons.) Twist a pipe cleaner for handling the butterfly larvae: Cut a 15-cm (6-in.) piece of pipe cleaner, then fold the last 5 cm (2 in.) of one end back upon itself, to form a flattened loop with no exposed metal. Tear off a 4-cm (1.6-in.) piece of masking tape for each team. broward county hands-on science Quarter 3 215
BACKGROUND INFORMATION As insects grow and develop, they go through distinct life stages, a process known as metamorphosis. Meta means change, and morpho means shape. Metamorphosis refers to the dramatic changes in shape or form that these insects experience. Both butterflies and moths begin life as eggs, hatch into larvae, eventually become pupae, and emerge from these as adults. During this process, they change completely in appearance. In the immature stage, the butterfly or moth is called a larva and often has a wormlike appearance. When such an insect transforms into a pupa, it is immobile, often having no familiar body parts, and the winged adult that emerges from the pupa has an entirely different appearance. The butterfly larvae you will receive with this kit are usually small (1 cm or 0.4 in. long) when they arrive and are dark in color with bristly hairs over most of their bodies (see Figure 21-1). The larvae will arrive in containers with food. The butterfly larvae s food is a greenish-brown paste with a distinctive odor. The butterfly larvae s food will readily support the growth of bacteria and mold, so be sure that anyone handling it carefully washes his or her hands before and after, to avoid contaminating the containers. The butterfly larvae s container is likely to have many small webs spun by the larvae as they move around. You may also see rounded bits of what looks like their food, but is actually their frass, or body waste. The butterfly larvae can be picked up easily by placing the looped end of the pipe cleaner next to them and gently rolling it until they cling on with their feet. The larvae do not bite. Each team of two will be setting up an individual container for its butterfly larva. 216 activity 21 Meet the Larvae Figure 21-1. The butterfly larvae. They will add the butterfly larvae food to their container before you place a butterfly larva in it. Since it is very easy to grow destructive bacteria and mold in the butterfly food container, it is important for everyone to wash his or her hands thoroughly before handling the containers, the spoons, the larvae food, the pipe cleaner, or the butterfly larvae.
Activity Sheet 21 Meet the Larvae 1. How long is a butterfly larva? Lengths will vary. cm 2. How does your butterfly larva move? Circle your answer. crawls flies 3. Draw your butterfly larva. 1 Guiding the Activity Show students the containers with the butterfly larvae and tell them that they will be studying butterflies in the following activities. Explain that these animals are young butterflies. Write larva and larvae on the board and explain that a larva is a young insect, and that larvae is the plural of larva. Ask, How should we treat the live animals we are studying? Additional Information Ask, What do all animals need to live? Explain that the food in the kit will provide the larvae with all the food and water they need, and that the larvae will have enough air and room to move around in the containers students place them in. Drawings will vary. They should be handled carefully and gently, and given everything they need to live. food, water, air, and room to move around The butterfly food is made from plant material. Remind students that animals depend on plants or other animals for food. broward county hands-on science Quarter 3 217
2 Guiding the Activity Distribute a copy of Activity Sheet 21 to each student, and a piece of masking tape and an empty 1-oz container with a lid to each team of two. Have students use the masking tape and markers to label the containers with their names. Additional Information If students have trouble writing legibly, you may want to number the containers and post a key to identify which container belongs to which team. Tell students they will be feeding their larvae specially prepared food for several days. In nature, butterflies lay their eggs on certain plants. When the larvae hatch, they eat the plant leaves. Thus, butterflies need plants for their offspring to grow. Have students wash their hands thoroughly, then collect larvae food for their containers from the distribution station. 218 activity 21 Meet the Larvae They should use the spoons to place a rounded teaspoon of the butterfly larvae food into the 1-oz container. It should be pressed firmly into the bottom of the container (see Figure 21-2). The food layer will be about 1 cm ( 1 / 2 in.) deep. Figure 21-2. Pack about 1 cm of larvae food tightly into the bottom of the 1-oz containers.
3 4 Guiding the Activity When the students have the butterfly containers clearly labeled and prepared with food, have them wash their hands again. Then, circulate through the classroom and gently place one butterfly larva into each team s container. Give each student a magnifier. When they have finished, have students place the containers to the sides of their desks. Explain to the students that they will be making ongoing observations of the larvae as they grow and change. Use the ruler to measure the length of an average-sized butterfly larva. Help students record this measurement on their activity sheets. Ask, What are some things you have observed about the butterfly larvae? Point out to students that although the larvae may look like small worms, they are not worms. They are young butterflies that will grow to look like their parents. The larvae must eat a lot of plant leaves to grow, which explains why butterflies lay their eggs on plants. Have students complete their activity sheets. Additional Information Conclude by reminding students that they will be observing the larvae over time to watch them grow and develop. Use the twisted pipe cleaner to lift the larvae gently: Place the twisted end of the pipe cleaner next to one of the larvae and roll it gently until the larva clings to it. Remove the larva from the pipe cleaner by gently rolling it off. This will help students be less distracted while having a discussion. Gently lift the larva onto a desk and move the zero marker on the ruler to one end of the larva s body. When the larva is stretched out fully, note where the other end of it falls on the ruler. Students are likely to say that the butterfly larvae are hairy or fuzzy, small, wiggly, dark in color, and have many legs. broward county hands-on science Quarter 3 219
R EINFORCEMENT Have students make models of the larvae using modeling clay and bits of toothpicks and pipe cleaners. SCIENCE JOURNALS Have students place their completed activity sheets in their science journals. C LEANUP Collect the butterfly larva containers and place in a spot away from direct sunlight or heat. Wash the spoons and return them to the kit, along with the masking tape and magnifiers. Refrigerate any extra butterfly larvae food. 220 activity 21 Meet the Larvae
Connections Science Challenge Support your explanation that butterfly larvae are not worms by having students look at pictures that show the differences between true worms and the wormlike larval stage of insects. Students will observe two major differences: (1) True worms have no legs, whereas insect larvae do, although the legs may be very tiny and difficult to see. (2) True worms do not go through changes in form as they develop. The tiny worm that emerges from an egg is fully developed and simply grows larger throughout its life. Provide an opportunity for students to observe differences between true worms and insect larvae by setting up a classroom culture of earthworms as described below. Earthworm culture: If earthworms cannot be collected in your area at the time of year you are doing this activity, you could purchase them from a commercial worm farm. Any plastic bucket or bin with a lid will make a suitable culture container. Fill the container about two-thirds full of potting soil. (Make sure the soil is free of insect larvae, pupae, and adults.) Mix in some shredded newspaper, leaves, or grass clippings, moisten the soil, and add the worms. Bury food scraps in the container from time to time. Explain that earthworms will not eat meat scraps or bones but will eat almost all types of fruits and vegetables cut into small pieces. At the conclusion of the activity (or when the season is appropriate), the soil and worms can be added to an outdoor garden. Science Extension As a class, look in encyclopedias or on the Internet to find out about the natural habitat and food of different types of butterflies. Science and the Arts Follow up the discussion of what all living organisms need to live by suggesting that students create individual posters for a display titled Meeting Their Needs. One poster should show how human beings meet their needs; others could be for a variety of animals, birds, and insects. Students can draw pictures or cut photos from magazines to illustrate their posters. Science and Health Point out to students that while the larvae food in the kit will give the larvae all the vitamins and minerals they need to live, the same diet would not be good for people. My Pyramid Plan is published by the United States Department of Agriculture on its Web site and provides information about daily nutritional needs for individuals. Give students a copy of the appropriate My Pyramid Plan for their age, or help them use the Internet to find it. Suggest that they use the information to prepare an illustrated pyramid showing a healthful diet for someone their age. Students can cut out or draw pictures of different foods to illustrate their pyramids. Science and Language Arts On the board, write 1 larva, 2 larvae. Remind students that not all words form the plural by adding -s or -es. Some words that come from Latin and end in the letter a form the plural the same way it was formed in Latin: by adding e. Begin a class chart with the headings One and More Than One. Write larva in the first column and larvae in the second column. Tell students that you will add other words to the chart as they learn about butterfly larvae. (The class will add to the chart in Activities 25 and 26.) broward county hands-on science Quarter 3 221
Connections Ask students whether they know another name for the larvae of butterflies. They will probably say caterpillar. Read from a dictionary about where the word caterpillar comes from and what it means. (from the Old North French catepelose, hairy cat ) Ask whether this is a good name for butterfly larvae. (Yes, because the larvae are hairy.) 222 activity 21 Meet the Larvae