Multiplying Fractions and Mixed Numbers

Please copy your Agenda for the week: Sept 14-18. Multiplying Fractions and Mixed Numbers CCSS.5NS.4 Multiply a whole number or fraction by a fraction. CCSS.6.NS.1 Multiplying fractions…real world problems. Essential Questions: Why would it be useful to know the greatest common factor of a set of numbers? What kind of models can I use to show solutions to word problems involving fractions? You will need your Math Journal open to the next clean page, a pencil, a red pen, 2 colored pencils, a highlighter, and glue.

Let’s discuss common errors made on the last quiz! Please fold your quiz in half and glue it into your Journal. Use your red pen to correct your errors on your quiz.

WARM UP: Think back to what you have learned about multiplying fractions to help Mark. • Mark is finding ¾ of 8. Find his mistake and correct it. x 8 =

Mark is finding ¾ of 8. Find his mistake and correct it. • Mark multiplied by instead of multiplying by . x = = 6 x 8 = Oops!

Review: Multiplying whole numbers and fractions: • Write the whole number as an improper fraction. Then multiply the numerators, multiply the denominators, and simplify if possible. Or simply multiply the whole number by the numerator, the denominator stays the same. Simplify. • EX. x x = = 2 • 5 x • 5 x = = 3 • Solve: 8 x • 8 x = = 3

Review: Multiplying fractions. Write this in your Journal! • Multiply the numerators, multiply the denominators, and simplify if possible. • Rick has of a footlong sub left from yesterday. He ate of the leftover sandwich as a snack. What fraction of the entire sandwich did he eat as a snack? x = of the sandwich

Simplify before multiplying using the GCF… Write this in your Journal! • If the numerators and the denominators have a common factor you can simplify before you multiply. If you cancel all the common factors using the GCFs before multiplying, the product will be in lowest terms. (Use 2 colored pencils for the example.) x = =

Simplify before multiplying using the GCF… Write this in your Journal! • If the numerators and the denominators have a common factor you can simplify before you multiply. If you cancel all the common factors using the GCFs before multiplying, the product will be in lowest terms. 1 3 x = 2 2

Practice this skill: • Glue the handout “A Shortcut for Multiplying Fractions” into your Math Journal. • Complete all work in your Journal. Show all steps, even if you can solve it mentally.  • Due tomorrow.

Sept. 15Please have your HW ready to grade. You need: Journal open to HW, red pen, pencil, highlighter…the usual…you need these items every day. Essential Question: Why would it be useful to know the greatest common factor of a set of numbers?

Copy into your Journal: Review: Writing Mixed Numbers as Improper Fractions • Multiply the whole number part and the denominator, add the numerator, and write the sum over the denominator. • Numbers: 1 ¾ = 4 x 1 + 3 = 7 4 4

Writing Improper Fractions as Mixed Numbers Write this in your Journal! • Divide the numerator by the denominator and write any remainder as a fraction. • Numbers: means 9 ÷ 2 = 4 r1 of 2, or 4 ½

Giant Squid…oh, my!!

Focus: Giant Squid Eye! • The eyeball of an Atlantic Giant Squid is about 12 times as large as the average human eyeball. The average human eyeball is 1 ¼ inches across. Use a bar diagram to compare the average size of a human eyeball to the average size of an Atlantic Giant Squid’s eyeball. |- - - - - - - - - - - - - - - - -squid eyeball- - - - - - - - - - - - - - -| |- - -| Human eyeball • Use the diagram above to compare the average size of the Atlantic Giant Squid’s eyeball to the average size of the human eyeball. Use repeated addition.

Focus: Giant Squid Eye! • |- - - - - - - - - - - - - - - - -squid eyeball- - - - - - - - - - - - - - -| |- - -| Human eyeball • Use the diagram above to compare the average size of the Atlantic Giant Squid’s eyeball to the average size of the human eyeball. Use repeated addition. • Write a multiplication expression that shows the size of the Atlantic Squid’s eyeball. • Write the multiplication expression using improper fractions. Multiply to find the size of the squid’s eyeball.

Multiplying Mixed Numbers and fractions…You will highlight this on your handout shortly. • First write the mixed number as an improper fraction. Remember that when mixed numbers are written as improper fractions, the denominator does not change. • Then multiply as with fractions. • Simplify if possible. • EX. 2 ½ x ¼ = x =

Multiplying Mixed Numbers • EX. The Hoover Dam contains 4 million cubic yards of concrete. The Grand Coulee Dam, in Washington State, contains 2 times as much concrete. How much concrete does it contain?

Left/Center/Right • Is the product of two mixed numbers greater than or less than both of the factors? • Move to the LEFT of the room if you think it is greater than. • Move to the RIGHT of the room if you think it is less than. • Move to the CENTER of the room if you think it depends on the mixed numbers. • BE ABLE TO JUSTIFY WHERE YOU MOVE.

HOMEWORK • Complete the practice worksheet “Multiplying Mixed Numbers Independent Practice”. Due tomorrow. You will have a quiz Friday over adding, subtracting, and multiplying fractions. • Thursday will be a practice day to review all of these skills. Come prepared to ask questions about skills you may be having a challenge with.

Multiplying Fractions and Mixed Numbers