What does dividing by 2 mean? _ in all _ equal groups _ in each group. Math Talk. Mathematical Processes

Transcription

1 ? Name 12.1 Essential Question Divide by 2 What does dividing by 2 mean? Number and Operations 3.4.H, 3.4.K Algebraic Reasoning 3.5.B MATHEMATICAL PROCESSES 3.1.C Unlock the Problem Hands On There are 10 hummingbirds and 2 feeders in Marissa s backyard. If there are an equal number of birds at each feeder, how many birds are at each one? Activity 1 Use counters to find how many in each group. Materials counters MathBoard What do you need to find? Circle the numbers you need to use. What can you use to help solve the problem? MODEL Use 10 counters. Draw 2 circles on your MathBoard. Place 1 counter at a time in each circle until all 10 counters are used. Draw the rest of the counters to show your work. THINK _ in all _ equal groups _ in each group RECORD 5 Image Credits: Visuals Unlimited/Corbis There are _ counters in each of the 2 groups. So, there are _ hummingbirds at each feeder. Math Talk Mathematical Processes Explain what each number in 10 2 = 5 represents from the word problem = 5 or 2 ) 10 Read: Ten divided by two equals five. A hummingbird can fly right, left, up, down, forward, backward, and even upside down! Module

2 Hands On Activity 2 Draw to find how many equal groups. There are 10 hummingbirds in Tyler s backyard. If there are 2 hummingbirds at each feeder, how many feeders are there? Math Idea You can divide to find the number in each group or to find the number of equal groups. MODEL Look at the 10 counters. Circle a group of 2 counters. Continue circling groups of 2 until all 10 counters are in groups. THINK _ in all _ in each group _ equal groups RECORD = 5 or 2 ) 10 Read: Ten divided by two equals five. There are _ groups of 2 counters. So, there are _ feeders. Share and Show 1. Complete the picture to find 6 2. _ Math Talk Mathematical Processes Describe another division equation that could be written for the picture you drew. Write a division equation for the picture

3 Name Problem Solving Use the table for Two hummingbirds of the same type have a mass of 10 grams. Which type of hummingbird are they? Write a division equation to show how to find the answer. Hummingbirds Mass Type (in grams) Magnificent 7 Ruby-throated 3 Violet-crowned 5 6. Multi-Step There are 3 ruby-throated hummingbirds and 2 of another type of hummingbird at a feeder. The birds have a mass of 23 grams in all. What other type of hummingbird is at the feeder? Explain. 7. Use Math Language There are 12 hummingbird eggs in all. If there are 2 eggs in each nest, how many nests are there? Explain how you found your answer. Image Credits: PhotoDisc/Getty Images 8. Multi-Step Becky made 2 video tapes while a giant hummingbird fed 4 times and a ruby throated hummingbird fed 8 times from her new feeder. Each video tape caught the same number of feedings by the hummingbirds. How many feedings were shown on each video tape? Justify your answer. Module 12 Lesson 1 361

4 Daily Assessment Task Mathematical Processes Fill in the bubble for the correct answer choice. Use models of each group or equal groups to help you solve. 9. Evaluate Danny is going to put his shoes away in pairs. He has 10 shoes. How many pairs of shoes does Danny put away? A 55 C 5 B 2 D For the field trip, pairs of students wore shirts of the same color. There were 18 students. How many different color shirts were there? A 11 C 15 B 9 D Multi-Step Luna s mom made 22 costumes for the class play. Half were for girls, and half were for boys. On the night of the show, one girl lost her costume and one boy ripped his. How many costumes for girls were left? A 11 C 9 B 20 D 10 TEXAS Test Prep 12. Jo sees the same number of birds each hour for 2 hours. She sees 16 birds in all. How many birds does Jo see each hour? 362 A 9 B 7 C 8 D 6

5 Homework and Practice Name Number and Operations 3.4.H, 3.4.K Algebraic Reasoning 3.5.B MATHEMATICAL PROCESSES 3.1.C 12.1 Divide by 2 Write a division equation for the picture Problem Solving Use the table for Two animals of the same kind have a total of 12 legs. Which animal is it? Write a division sentence to show how to find the answer. Legs on Animals Animal Number of Legs Spider 8 Beetle 6 Frog 4 Duck 2 4. There are 4 frogs and 3 different animals at a pond. The animals have a total of 22 legs in all. What other kind of animal is at the pond? Explain. 5. There are 16 boots on a shelf. If there are 2 boots in each pair, how many pairs of boots are there? Explain. Module 12 Lesson 1 363

6 Lesson Check TEXAS Test Prep Fill in the bubble completely to show your answer. 6. A bus has 18 students. The students are seated in twos. How many seats do the students take up on the bus? A 18 B 9 C 16 D 8 7. There are 16 students playing a game. Each student has a partner. How many pairs of partners are playing the game? A 7 B 14 C 8 D Demarcus likes to watch butterflies. He counts a total of 10 wings in all. If each butterfly has a pair of wings, how many butterflies does Demarcus see? A 20 B 10 C 5 D 2 9. Tanya makes a bracelet with 20 beads. She makes a repeating pattern of two red beads and two blue beads. How many patterns are there? A 4 B 16 C 5 D Multi-Step A store has 14 gloves. Two of the pairs are black. The rest are brown. How many pairs of brown gloves are there? 364 A 5 B 8 C 12 D Multi-Step Lin makes a tile design with 24 tiles. Half are red and half are blue. He takes away 4 red tiles. How many red tiles are in the design now? A 20 B 8 C 12 D 28