Areas of Rectangles
Transcription
Areas of Rectangles
Areas of Rectangles Objective To reinforce students’ understanding of area concepts and units of area. c www.everydaymathonline.com ePresentations eToolkit Algorithms Practice EM Facts Workshop Game™ Teaching the Lesson Family Letters Assessment Management Common Core State Standards Ongoing Learning & Practice Key Concepts and Skills Fraction Division Review • Multiply fractions and mixed numbers to find the area of a rectangle. Math Journal 2, p. 306 Student Reference Book, pp. 80–80B Students use visual models and number stories to solve fraction problems. [Operations and Computation Goal 5] • Use a formula to calculate the areas of rectangles. [Measurement and Reference Frames Goal 2] • Compare inch and centimeter measures for length and area. [Measurement and Reference Frames Goal 3] Curriculum Focal Points Interactive Teacher’s Lesson Guide Differentiation Options READINESS Comparing Perimeter and Area Math Boxes 9 4 Math Masters, p. 266 per partnership: 2 six-sided dice, 36 centimeter cubes Students use centimeter grids to compare the perimeters and areas of rectangles. Math Journal 2, p. 307 Students practice and maintain skills through Math Box problems. Comparing Perimeter and Area for Irregular Figures Key Activities Study Link 9 4 Students review area concepts and the names and notations for common area units. They find areas of rectangles by counting and by applying an area formula. Math Masters, p. 265 Students practice and maintain skills through Study Link activities. Ongoing Assessment: Informing Instruction See page 725. Ongoing Assessment: Recognizing Student Achievement Use an Exit Slip (Math Masters, page 414). [Measurement and Reference Frames Goal 2] Key Vocabulary area square units base height formula variable ENRICHMENT Math Masters, pp. 267 and 436 3 different-colored pencils or markers scissors Students compare the perimeters and areas of irregular polygons. EXTRA PRACTICE 5-Minute Math 5-Minute Math™, p. 212 Students calculate the areas of rectangles. EXTRA PRACTICE Area: Tiling and Using a Formula Math Masters, pp. 293A and 436 Students find the areas of rectangles with fractional units by tiling and using a formula. ELL SUPPORT Materials Math Journal 2, pp. 304 and 305 Student Reference Book, p. 188 Study Link 93 Math Masters, p. 414 transparency of Math Masters, p. 436 Class Data Pad inch ruler slate roll of paper towels, wax paper, or aluminum foil (optional) Building a Math Word Bank Differentiation Handbook, p. 142 Students define and illustrate the terms length, height, base, and width. Advance Preparation For Part 1, display a set of unit squares. (See Planning Ahead, Lesson 9-2.) Use a roll of paper or foil to demonstrate carpet rolls for Math Journal 2, page 305, Problem 2. Teacher’s Reference Manual, Grades 4–6 pp. 220–222, 233, 234, 236 722 Unit 9 Coordinates, Area, Volume, and Capacity 722_EMCS_T_TLG2_G5_U09_L04_576914.indd 722 4/7/11 9:25 AM Getting Started Mental Math and Reflexes Math Message Have students write fractions as equivalent decimals and percents. Suggestions: Read page 188 of the Student Reference Book, and write two important facts about area. 2 2 _ ⎯⎯; 66 _ 0.66 % 3 3 4 _ 0.8; 80% 5 8 _ 0.32; 32% 25 19 _ 0.95; 95% 20 24 _ 0.48; 48% 50 3 _ 0.375; 37.5% 8 Study Link 9 3 Follow-Up Have partners compare answers and resolve any differences. 1 Teaching the Lesson ▶ Math Message Follow-Up WHOLE-CLASS DISCUSSION (Student Reference Book, p. 188) Ask volunteers to share what they wrote about area. Use their responses and the display of common units of area to review basic area concepts. Emphasize the following points: Area is a measure of the surface, or region, inside a closed boundary. It is the number of whole and partial unit squares needed to cover the region without gaps or overlaps. NOTE It is more precise to talk about the area of a rectangular region, the area of a triangular region, and so on. However, it is customary to refer to area in terms of the figure that is the boundary: the area of a rectangle, the area of a triangle, and so on. Area is measured in square units. There are many units to choose from, and some choices make more sense than others. Call students’ attention to the classroom display of unit squares and to alternative ways of writing the units: square inch, sq in., or in2; square meter, sq m, or m2; and so on. Ask students to share the relationships they observe among the units—for example, a square meter is larger than a square yard. There are 9 square feet in a square yard and 144 square inches in a square foot. A square inch is larger than a square centimeter. Student Page Measurement Area Area is a measure of the amount of surface inside a closed boundary. You can find the area by counting the number of squares of a certain size that cover the region inside the boundary. The squares must cover the entire region. They must not overlap, have any gaps, or extend outside the boundary. 1 cm 1 cm 1 square centimeter (actual size) Sometimes a region cannot be covered by an exact number of squares. In that case, count the number of whole squares and fractions of squares that cover the region. 1 in. 1 in. Area is reported in square units. Units of area for small regions are square inches (in.2), square feet (ft2), square yards (yd2), square centimeters (cm2), and square meters (m2). For large regions, square miles (mi2) are used in the United States, while square kilometers (km2) are used in other countries. 1 square inch (actual size) You may report area using any of the square units. But you should choose a square unit that makes sense for the region being measured. Examples The area of a field-hockey field is reported below in three different ways. Area of the field is 6,000 square yards. Area of the field is 54,000 square feet. Area of the field is 7,776,000 square inches. Area ⫽ 6,000 yd Area ⫽ 54,000 ft Area ⫽ 7,776,000 in.2 2 2 100 yd 60 yd 300 ft 180 ft 3,600 in. 2,160 in. Although each of the measurements above is correct, reporting the area in square inches really doesn’t give a good idea about the size of the field. It is hard to imagine 7,776,000 of anything! The International Space Station (ISS) orbits the Earth at an altitude of 250 miles. It is 356 feet wide and 290 feet long, and has an area of over 100,000 square feet. Student Reference Book, p. 188 Lesson 9 4 723-728_EMCS_T_TLG1_G5_U09_L04_576914.indd 723 723 2/15/11 7:00 PM Student Page Date Time LESSON ▶ Finding the Area of a Rectangle Areas of Rectangles 1 cm2 1 cm 1 cm D Ask volunteers to define the terms base and height. The term base is often used to mean both a side of a figure and the length of that side. The height of a rectangle is the length of a side adjacent to the base. base (or length) E B A Fill in the table. Draw rectangles D, E, and F on the grid. Rectangle Base (length) 2 4 2.5 A B C 2. Ask students to decide upon the phrasing of a common definition for these vocabulary terms. Record the student definitions on the Class Data Pad. F C 1. PARTNER ACTIVITY (Math Journal 2, p. 304) height (or width) 94 D 6 cm E 3.5 cm F 3 cm Height (width) cm cm cm 5 4 2.5 2 4 3.5 cm cm cm cm Ask a volunteer to draw a rectangle on the board and label the base and height. Area 10 16 6.25 cm2 cm2 cm2 12 cm2 cm 14 cm2 cm 10.5 cm2 height Write a formula for finding the area of a rectangle. Area = base ∗ height (b ∗ h), or length ∗ width (l ∗ w) base Math Journal 2, p. 304 292-332_EMCS_S_G5_MJ2_U09_576434.indd 304 2/22/11 5:18 PM In Fourth Grade Everyday Mathematics, students found the area of a rectangle by counting unit squares. Then they developed a formula for finding the area of a rectangle. Expect that students might use either method—formula or counting squares—to find the areas of the rectangles on journal page 304. With the counting method, some rectangles enclose partial grid squares, and students must count and add the full and partial squares to find areas. For example, rectangle C encloses 1 = 2 cm2), and 4 full squares (4 cm2), 4 half-squares (4 ∗ _ 2 1 cm2). Its total area is 4 + 2 + _ 1 = 6_ 1 cm2. 1 quarter-square (_ 4 4 4 4 full squares 4 cm2 4 half-squares 2 cm2 +1 quarter-square 1 cm2 _ total area 1 cm2 6_ 4 4 Each half-square has an area 1 cm2. of _ 2 1 cm The quarter-square is _ 2 1 cm wide. long and _ 2 1 cm2 1 cm 1 cm C Assign journal page 304, Problem 1. Circulate and assist. 724 Unit 9 Coordinates, Area, Volume, and Capacity 723-728_EMCS_T_TLG2_G5_U09_L04_576914.indd 724 3/23/11 2:47 PM ▶ Discussing Formulas for WHOLE-CLASS DISCUSSION the Area of a Rectangle (Math Journal 2, p. 304; Math Masters, p. 436) Algebraic Thinking Ask volunteers to give the dimensions of rectangles A–F as other volunteers draw the rectangles on a transparency of Math Masters, page 436. Ask: What do you notice about the relationship between the base and height and the actual area of each figure? The base multiplied by the height is equal to the area. Reinforce this rule: If the length of the base and the height of a rectangle are known, the area can be found by multiplying the length of the base by the height. Such a rule is called a formula. The formula can be written in abbreviated form as: NOTE An alternative formula for the area of a rectangle is A = l ∗ w, where l stands for the length and w stands for the width of the rectangle. Students are familiar with both versions of the formula from Fourth Grade Everyday Mathematics. A = b ∗ h, where A stands for the area, b stands for the length of the base, and h stands for the height. Ask students to complete Problem 2 on journal page 304. Remind students that letters used in this way are called variables. Add the abbreviated formula to the definitions on the Class Data Pad, and have students write the abbreviated formula after their answers for Problem 2 on journal page 304. Refer students to the rectangles drawn on the transparency. Have students apply the formula for the rectangles in Problem 1. Ask volunteers to record a number model for the area of each rectangle on the transparency. For example, 2 cm ∗ 5 cm = 10 cm2. Have students check their total count of the squares with the product from the number model. For rectangles C and E, ask students to 1 cm ∗ 2_ 1 cm = 6_ 1 cm2, think about the decimals as fractions (2_ 2 2 4 1 cm = 14 cm2). and 4 cm ∗ 3_ 2 Ask partners to estimate, in inches, the length of the sides of the rectangles on journal page 304. Then have students measure the sides of rectangle C using their inch rulers. (Each side of rectangle C is about 1 inch long.) Ask students what the area of rectangle C is when the unit is inches. 1 square inch Point out that there are 1 centimeters in 1 inch, and about 6.25, or 6_ 1 about 2.5, or 2_ 2 4 square centimeters in 1 square inch. Student Page Date Time LESSON Area Problems 9 4 1. A bedroom floor is 12 feet by 15 feet (4 yards by 5 yards). Floor area = Floor area = 2. 3. 12 ft (4 yd) square yards 6 ft (2 yd) 30 ft, or 10 yd 4. Calculate the areas for the figures below. 9 yd Fill in the missing lengths for the figures below. a. 12 ft 6 yd PROBLEM PR PRO P RO R OBL BLE B LE L LEM EM SO S SOLVING OL O LV VIN IIN NG N G Have students complete journal page 305. Circulate and assist. 12 yd INDEPENDENT ACTIVITY 6 yd (Math Journal 2, p. 305) square feet Imagine that you want to buy carpet for the bedroom in Problem 1. The carpet comes on a roll that is 6 feet (2 yards) wide. The carpet salesperson unrolls the carpet to the length you want and cuts off your piece. What length of carpet will you need to cover the bedroom floor? a. ▶ Applying the Area Formulas 180 20 15 ft (5 yd) 6 yd 30 ft 30 360 ft2 ft 3 yd Area = 72 b. yd2 b. 12 12 ft 12 ft 15 yd 4 ft 8 ft 4 12 ft 2 ft Area = 76 ft2 25 yd 375 yd2 15 25 yd yd Math Journal 2, p. 305 292-332_EMCS_S_MJ2_G5_U09_576434.indd 305 3/22/11 12:42 PM Lesson 9 4 723-728_EMCS_T_TLG2_G5_U09_L04_576914.indd 725 725 4/7/11 9:30 AM Student Page Date Time LESSON 2. 9 Liz, Juan, and Michael equally share _ 12 of a pizza. a. To show how the 9 pieces can be distributed, write the student’s initial on each piece that he or she is getting. b. Each student will get c. Write a number model to show what fraction of the whole pizza each student gets. 3 J M L L pieces. M J 9 _ 0 12 1 FEET 2 3 18 4 5 18 1 players. So, 6 ÷ _ 3 = 6 . 1 _ Write an open number model to show how much of Mr. Shower’s prize went to each department. 2 1 _ b. 5. 3 1 _ ÷3=_ 12 , or 4 When Mr. Showers won a large amount of money, he donated half to a local college. The funds were divided equally among 5 departments. a. 4. Watch for students who hesitate with Problem 2. Ask: Which unit makes more sense to work with, feet or yards? yards Refer students to Problem 1 and ask how many yards of carpet are needed. 20 square yards Illustrate Problem 2 using a roll of paper towels, waxed paper, or aluminum foil to demonstrate how a piece of carpet is cut from a roll. As the “carpet” unrolls, the area increases. For example, in Problem 2, each foot unrolled adds an additional 6 square feet or 2 square yards. As you unroll the model, have students shade the grid in Problem 1 to show how much floor is covered. Prompt students to tell you where to cut the model. J M L A football team orders a 6-foot-long submarine sandwich. Each player 1 will eat _ 3 of a foot of sandwich. Draw tick marks on the ruler to help you find how many players the sandwich will serve. The sandwich will serve 3. Ongoing Assessment: Informing Instruction Fraction Division Review 9 4 1. 10 Each department received When most students have completed the journal page, ask volunteers to share their solution strategies. Ask questions like the following: ÷5=p of the prize. The stone is a unit of weight used in the United Kingdom 1 and Ireland. One pound equals _ 14 stone. Anna’s pen pal in Ireland weighs 6 stones. How much is this in pounds? 84 pounds ● 1 Write a number story that can be solved by dividing 3 by _ 4 . Solve your problem. Answers vary. Math Journal 2, p. 306 292-332_EMCS_S_MJ2_G5_U09_576434.indd 306 In Problem 2, how will you cut the carpet to make it fit the bedroom? If students determine that they will need a piece of carpet 30 feet or 10 yards long, they will need to cut it in half to fit the bedroom. Each of the two pieces will be 2 yards by 5 yards. 4/6/11 11:01 AM 2 yd 10 yd 2 yd 4 yd 2 yd 5 yd ● Student Page Date Time LESSON Math Boxes 9 4 In Problem 4, how did you find the missing lengths? Encourage students to use multiplication/division relationships and open number sentences. For example, 360 ÷ 12 = h, or 25 ∗ b = 375. 3 _ 1. A rope 4 meter long is cut into 6 equal pieces. 2. What is volume of the prism? Choose the best answer. 3 4 0 240 units3 meters a. b. 30 units3 Write a number model to describe the problem. 4 3. 90 units2 Draw lines on the rope to show how long each piece will be. 3 _ ÷ 6 = _18 90 units3 > 8 * 105 4. b. 12.4 million c. 7,000,000 d. 82 e. 5.4 * 102 < = > 429 * 15 6,435 12,400,000 7 * 105 c. 28 < Solve. a. 80,000 b. 134 * 82 10,988 706 *189 [Measurement and Reference Frames Goal 2] 133,434 5,400 220 221 5. false true 86,076 is divisible by 9. true 908,321 is divisible by 2. false 5,278 is divisible by 3. b. 79,002 is divisible by 6. c. d. 19 20 6. Write true or false. a. Exit Slip Use an Exit Slip (Math Masters, page 414) to assess students’ ability to calculate area. Have students write a response to the following: Explain how you found the area for the figure in Problem 3b on journal page 305. Students are making adequate progress if they multiply the side lengths to find the areas of the rectangles in order to find the total area. 197 80A 80B Compare. Use <, >, or =. a. Ongoing Assessment: Recognizing Student Achievement 1 11 Complete the “What’s My Rule?” table, and state the rule. Rule: ∗2+1 in out 4 9 7 15 11 23 9 19 6 13 231 232 Math Journal 2, p. 307 292-332_EMCS_S_MJ2_G5_U09_576434.indd 307 726 Unit 9 4/6/11 11:01 AM Coordinates, Area, Volume, and Capacity 723-728_EMCS_T_TLG2_G5_U09_L04_576914.indd 726 4/7/11 9:30 AM Study Link Master Name 2 Ongoing Learning & Practice ▶ Fraction Division Review PARTNER ACTIVITY Date STUDY LINK Time More Area Problems 9 4 1. Rashid can paint 2 square feet of fence in 10 minutes. Fill in the missing parts to tell how long it will take him to paint a fence that is 6 feet high by 25 feet long. Rashid will be able to paint 150 sq ft of fence in . 12 hr 30 min 2. Regina wants to cover one wall of her room with wallpaper. The wall is 9 feet high and 15 feet wide. There is a doorway in the wall that is 3 feet wide and 7 feet tall. How many square feet of wallpaper will she need to buy? (hours/minutes) (area) (Math Journal 2, p. 306; Student Reference Book, pp. 80–80B) 104 105 189 114 square feet Have students review information about fraction division problems on pages 80–80B of the Student Reference Book. Discuss the use of visual models and number stories. Then have students complete the journal page. Calculate the areas for the figures below. 3. 4. 4 yd 1 ft 2 ft 12 yd 4 yd 9 ft 4 ft 4 yd 10 yd 2 ft ▶ Math Boxes 9 4 INDEPENDENT ACTIVITY 5. Mixed Practice Math Boxes in this lesson are paired with Math Boxes in Lesson 9-2. The skill in Problem 6 previews Unit 10 content. Writing/Reasoning Have students write a response to the following: Explain how you could determine the volume of the rectangular prism in Problem 2 by counting the unit cubes. Then write a number model for the formula you could use to find the volume. Sample answers: I could count the number of unit cubes in the bottom layer first. The width is 6 and the length of the base is 5. So there are 30 unit cubes in the bottom layer. The height is 3, so there are three layers of 30. The volume is 90 units3. The formula is B ∗ h = V. The number model is (5 ∗ 6) ∗ 3 = 90 units3. 80 yd2 Area = 33 Fill in the missing lengths for the figures below. (Math Journal 2, p. 307) ▶ Study Link 9 4 Area = 6m 60 cm 3,000 cm 2 ft 2 33 m 6. 50 cm 5 ft 198 m 2 60 cm 6m 33 m 50 cm Math Masters, p. 265 254-293_497_EMCS_B_MM_G5_U09_576973.indd 265 3/23/11 1:09 PM INDEPENDENT ACTIVITY (Math Masters, p. 265) Teaching Master Home Connection Students solve area problems. Name LESSON 9 4 Date Roll 2 six-sided dice. The numbers on top are the lengths of 2 sides of a rectangle. 3 Differentiation Options READINESS ▶ Comparing Perimeter and Area PARTNER ACTIVITY Time Comparing Perimeter and Area Rectangle Draw the rectangle in the grid below. A Record the perimeter and the area of the rectangle in the table. B Use centimeter cubes to find other rectangles that have the same area, but different perimeters. Draw the rectangles and record their perimeters and areas in the table. Perimeter Area Answers vary. C D E F Repeat until you have filled the table. You might need to roll the dice several times. 5–15 Min (Math Masters, p. 266) To support students’ understanding of perimeter and area, have partners roll 2 six-sided dice to determine the dimensions of a rectangle. They draw a rectangle with those dimensions and find the perimeter and area of the rectangle. Partners then find other rectangles with the same area, but different perimeters. They repeat this process until the table on page 266 is completed. Discuss what conclusions can be drawn from the table. Sample answers: Different perimeters can have the same area; the dimensions are factor pairs for the area. Math Masters, p. 266 254-293_497_EMCS_B_MM_G5_U09_576973.indd 266 3/23/11 1:09 PM Lesson 9 4 723-728_EMCS_T_TLG2_G5_U09_L04_576914.indd 727 727 4/7/11 9:30 AM Teaching Master Name Date LESSON Time 9 4 ▶ Comparing Perimeter and Cut 6 rectangles that are 6 columns by 7 rows from the centimeter grid paper. Record the area and the perimeter of one of these rectangles in Problem 1. Divide each rectangle by using 3 different colored pencils to shade three connected parts with the same number of boxes. The parts must follow the grid, and the squares must be connected by sides. Area for Irregular Figures Divide each rectangle in a different way. (Math Masters, pp. 267 and 436) 1. 42 cm 2 Perimeter = 26 cm To apply students’ understanding of perimeter and area to irregular figures, have partners divide rectangles and compare the relationship between perimeter and area. When students have finished, have them share the parts they cut from their rectangles and discuss questions such as the following: Record the perimeters for the divisions of the 6 rectangles in the table. Perimeters Rectangle Part 1 1 Part 2 Part 3 Answers vary. 2 3 4 5 6 14 square centimeters What is the range of the perimeters for each of the parts? Answers vary. ● Can you use the area of a figure to predict the perimeter of that figure? No ● Can you use the perimeter of a figure to predict the area of that figure? No 4. 5. a. py g p What is the area for each of the parts? g 3. 15–30 Min For a rectangle that is 6 cm by 7 cm: Area = 2. PARTNER ACTIVITY ENRICHMENT Perimeter and Area of Irregular Figures b. Describe one relationship between perimeter and area. Sample answer: Shapes with the same area can have different perimeters. Is the relationship the same for rectangles and irregular figures? Explain. Guide students to conclude that perimeter and area are independent measures. Answers vary. Math Masters, p. 267 254-293_497_EMCS_B_MM_G5_U09_576973.indd 267 EXTRA PRACTICE 3/23/11 1:09 PM ▶ 5-Minute Math SMALL-GROUP ACTIVITY 5–15 Min To offer students more experience with calculating the area of rectangles, see 5-Minute Math, page 212. EXTRA PRACTICE ▶ Area: Tiling and Using PARTNER ACTIVITY 15–30 Min a Formula (Math Masters, pp. 293A and 436) Teaching Master Name Date LESSON 94 To find the area, students use grid paper to tile rectangles that have fractional side lengths. They also use the formula for the area of a rectangle to show that both methods produce the same result. Time Area: Tiling and Using a Formula For each rectangle below, cut out a rectangle from the centimeter grid paper (Math Masters, page 436) that has the same dimensions. Follow the directions for each problem. 1. The length of the base of the rectangle 1 is 6 cm and the height is 2_2 cm. ELL SUPPORT 2. a. Tape the centimeter grid over the rectangle, and then use the counting method to find the area of the rectangle. b. Use the formula to write an open number model that can be used to find the area. c. Area = 15 15 cm _ 6 ∗ 2 12 = A ▶ Building a Math Word Bank 2 SMALL-GROUP ACTIVITY 5–15 Min (Differentiation Handbook, p. 142) cm2 The length of the base of the rectangle below is 12_2 cm and the height is 2_2 cm. 1 1 a. Tape the centimeter grid over the rectangle, and then use the counting method to find the area of the rectangle. b. Use the formula to find the area. b. Use the formula to find the area of the rectangle below. 4 cm2 cm2 p 1 1_2 cm g Tape the centimeter grid over the rectangle, and then use the counting method to find the area of the rectangle. cm2 cm2 py g 3. a. 31_14 31_14 15_34 15_3 To provide language support for area, have students use the Word Bank Template found on Differentiation Handbook, page 142. Ask students to write the terms length, height, base, and width; draw pictures relating to each term; and write other related words. See the Differentiation Handbook for more information. 10 _2 cm 1 c. Explain why the formula and the counting method produce the same area. Sample answer: Each row has the same number of squares. So, multiplying the base by the height gives you the number of squares there are in all. Counting the squares gives you the same area. Math Masters, p. 293A 293A_EMCS_B_MM_G5_U09_576973 .indd 293A 728 Unit 9 3/22/11 9:31 AM Coordinates, Area, Volume, and Capacity 723-728_EMCS_T_TLG2_G5_U09_L04_576914.indd 728 3/23/11 2:47 PM Name Date LESSON 94 Time Area: Tiling and Using a Formula For each rectangle below, cut out a rectangle from the centimeter grid paper (Math Masters, page 436) that has the same dimensions. Follow the directions for each problem. 1. The length of the base of the rectangle 1 is 6 cm and the height is 2_2 cm. a. 2. Tape the centimeter grid over the rectangle, and then use the counting method to find the area of the rectangle. b. Use the formula to write an open number model that can be used to find the area. c. Area = cm2 cm2 1 1 The length of the base of the rectangle below is 12_2 cm and the height is 2_2 cm. a. b. b. cm2 Use the formula to find the area. cm2 Use the formula to find the area of the rectangle below. cm2 Tape the centimeter grid over the rectangle, and then use the counting method to find the area of the rectangle. cm2 1_2 cm 1 10 _2 cm 1 c. Copyright © Wright Group/McGraw-Hill 3. a. Tape the centimeter grid over the rectangle, and then use the counting method to find the area of the rectangle. Explain why the formula and the counting method produce the same area. 293A 293A_EMCS_B_MM_G5_U09_576973 .indd 293A 3/22/11 9:31 AM