Melvin, Morris and Mom go Shopping in Cozumel! Common Core Math: Grade 4: Standard 4.OA.3 Melvin, Morris and Mom go Shopping in Cozumel! 4.OA.3 Solve multistep word problems posed with whole numbers and having whole-number answers using the four operations, including problems in which remainders must be interpreted. Represent these problems using equations with a letter standing for the unknown quantity. Assess the reasonableness of answers using mental computation and estimation strategies including rounding. © abcteach 2012

Common Core Math: 4.OA.3 Mom took us shopping at her favorite jewelry store in Cozumel, Mexico. She wanted to buy pearl necklaces as Christmas presents for her friends. She knew that cultured pearls cost $1.50 an inch. She had saved $200.00 to buy necklaces. She wanted all of the necklaces to be the same length. The sales lady showed mom three different length necklaces. Mom thought for a long time about which necklaces to buy. One of the things that she thought about was how many of each length of necklace she could buy for $200.00. Click to see the table mom made to organize her thinking! Length Cost How Many? 16 inches $24.00 20 inches $30.00 24 inches $36.00 © abcteach 2012

Common Core Math: 4.OA.3 Work with a partner and figure out how many of each length of necklace Mom can buy with $200.00. Click once to see the table mom made. When you and your partner are done, click each line to see if you were right! Length Cost How Many? 16 inches $24.00 20 inches $30.00 24 inches $36.00 8 6 5 © abcteach 2012

Common Core Math: 4.OA.3 How did YOU figure out how many of each length necklace Mom could buy with $200.00? Here’s one way Melvin thought of…. He told me he started with the 16 inch pearl necklace. He knew each one cost $24. He said, “24 is close to 25. I know that 25 X 4 = 100, so 25 X 8 must = 200. So, mom can buy eight 16 inch necklaces for $200.00. AND she will have $8.00 left over. I figured that out because 24 is 1 less than 25. I have 8 groups of 24. 8 X 1=8, so she will have $8.00 left over!” © abcteach 2012

8 8 192 - I told Melvin there was a MUCH easier way to figure it out! Common Core Math: 4.OA.3 I told Melvin there was a MUCH easier way to figure it out! “Here’s how I figured it out. I simply divided 200 by 24. 200 divided by 24 is 8. There are eight dollars left over.” 8 192 - No, there isn’t! 8 So, mom could buy eight 16 inch pearl necklaces with $200! YES, there IS! © abcteach 2012

I figured out an even EASIER Way! Common Core Math: 4.OA.3 Melvin told me there was an even EASIER way to figure it out! I think that MY WAY is the very best, but I listened anyway. (Mom started giving me THAT look!) Melvin said, “Check this out! $24 + $24 = $48. (That’s two 16 inch necklaces.) $48 + $48 = $96. (That’s four 16 inch necklaces.) $96 + $96 = $192. (That’s eight 16 inch necklaces!) He paused dramatically, and then said, “Guess what?” I figured out an even EASIER Way! I KNEW what was coming next….. “There’s eight dollars left over because $200 - $192 = $8” No, you DIDN’T! © abcteach 2012

Common Core Math: 4.OA.3 Share out with the class how you and your partner figured out how many 20 and 24 inch long pearl necklaces mom could buy with $200.00. © abcteach 2012

Common Core Math: 4.OA.5 Mom wanted to buy her best friend one set of pearl necklaces of all three different lengths. Also, she wanted to buy as many necklaces as possible. She wanted to spend as close to $200.00 as possible. What combination of necklaces did she buy? Work with your partner to find the answer. Show all work. Be ready to share your answer and thinking with the class! Length Cost How Many? 16 inches $24.00 20 inches $30.00 24 inches $36.00 © abcteach 2012

The most necklaces she could buy and spend close to $200; Common Core Math: 4.OA.3 Problem and Solution: Mom wanted to buy her best friend one set of pearl necklaces of all three different lengths. After this, she wanted to buy as many necklaces as possible. She wanted to spend as close to $200.00 as possible. What combination of necklaces did she buy? The most necklaces she could buy and spend close to $200; Three 16 inch = $72 One 24 inch = $36 One set of 3 =$90 Total = $198 and $2 left over. Length Cost How Many? 16 inches $24.00 20 inches $30.00 24 inches $36.00 © abcteach 2012