Fractions lesson 10
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This document provides an overview of multiplying fractions. It begins with a review of fractions, including the definition of a fraction as part of a whole and the meaning of the numerator and denominator. It then discusses how to multiply fractions by multiplying the numerators and denominators. Multiplying fractions means finding a fraction of a fraction. The document provides examples of multiplying fractions, mixed numbers, and cancelling common factors before multiplying. Students are given practice problems and homework assignments.
Fractions lesson 10
- 1. Fractions lesson 10 MULTIPLYING FRACTIONS
- 2. Quick Review What are Fractions? Part of the whole The Top number is the _____________. Numerator The Bottom number is the ____________. Denominator What are the 3 types of fractions? Proper Improper Mixed Numbers
- 3. Quick Review What information does the denominator give? The number of parts that the whole is divided into! What information does the numerator give? The number of parts from the whole
- 4. Quick Review What is the difference between a mixed number and an improper fraction? A mixed number is a number whose value is greater than 1 made up of a whole part and a fraction part and an improper fraction is a fraction whose value is greater than or equal to 1 (numerator greater than or equal to denominator)
- 5. Quick ReviewDoes anyone know how to convert from a mixed number to an improper fraction? Multiply the whole number times the denominator. Add your answer to the numerator. Put your new number over the denominator. Does anyone know how to convert from an improper fraction to a mixed number ? Divide the numerator by the denominator. The dividend becomes the whole number part. Put your remainder over the denominator, which will make up the fraction part.
- 6. Quick Review What are the three steps to reading fractions on a number line? Step 1: Count the spaces in between the whole numbers where the fraction is placed. That is your denominator. Step 2: Count the sticks, starting at the first stick after the whole number. Stop at the point you are naming. This is the Numerator Step 3: Write the whole number as a whole number beside the fraction
- 7. Quick Review What is an equivalent fraction? They are fractions that have the same value! How do you make equivalent fractions? You multiply or divide the numerator and the denominator by the same number!
- 8. Quick Review How do you reduce or simplify fractions? Divide both the numerator and the denominator by the GCF! How do you compare fractions? You use bottoms up
- 9. Quick Review What are like and unlike fractions?? Like fractions are fractions with the same denominators and unlike fractions are fractions with different denominators! How do you compare like fractions? By comparing their numerators How do you compare unlike fractions? By using bottoms up!
- 10. What process do you follow when adding or subtracting fractions? Are the denominators the same? Make equivalent fractions with the same denominator using bottoms up or LCM. Add the numerators and simplify where necessary Add the numerators Simplify the fraction if necessary
- 11. Quick Review How do you add mixed fractions? Separate the fraction and the whole number sections, add them separately and recombine at the end! What if the numerator is bigger than the denominator? Convert to a mixed a number What if it’s already a mixed number? Then add the 2 whole number parts together!
- 12. Quick Review How do you subtract mixed fractions? Convert to a improper fraction Make equivalent fractions using bottoms up Subtract Simplify Convert back to a mixed number
- 13. Today’s Lesson We are going to look at multiplying fractions This will be important when dividing fractions so pay attention
- 15. It is repeated addition!
- 16. So… 5 × 5 = 25 5 + 5 + 5 + 5 + 5 = 25
- 17. But does the same apply to fractions? 2 3 × 7 = 2 3 + 2 3 + 2 3 + 2 3 + 2 3 + 2 3 + 2 3 = 14 3 = 4 2 3 14 3 = 4 2 3 Yes it does!!!
- 18. But what about multiplying fractions with fractions…?
- 19. That’s easy…
- 20. You multiply the numerator with the numerator and the denominator with the denominator 3 5 × 7 11 = 21 55
- 21. But what does that even mean?
- 22. Multiplying fractions basically means finding a fraction of a fraction In the previous example, we found out what 7 11 𝑜𝑓 3 5 is
- 23. Multiplying fractions basically means finding a fraction of a fraction So first we shade in 3 5 of the given shape
- 24. Multiplying fractions basically means finding a fraction of a fraction Then for every 11 pieces in the shaded region, we shade in 7, then count up how many pieces from the whole we have
- 25. Now you try... Multiply the following: 4 2 9 3 1 5 3 8 2 4 3 5 5 5 8 8
- 26. Answers 4 2 8 9 3 27 1 5 5 3 8 24 2 4 8 3 5 15 5 5 25 8 8 64
- 27. Multiplying Mixed Numbers First, convert to improper fractions Then multiply Remember to convert back to mixed numbers 2 1 2 × 1 1 4 = 5 2 × 5 4 = 25 8 = 3 1 8
- 28. Now you try… 8 5 1 5 2 3 1 3 5 × 5 1 3 = 17 5 × 13 8 8 5 × 16 3 = 128 15 = 221 40 = 5 21 40 = 8 8 15
- 29. Cancelling Cancelling is a way of simplifying fractions before you multiply them THIS ONLY APPLIES WITH MULTIPLICATION This happens between the numerator of one fraction and the denominator of the other 1120 300 35 12 32 25 Has a common factor of 5 Has a common factor of 4 = 5 8 × 3 7 = 15 56
- 30. Now you try… 10 1 3 5 4 15 14 2 1 4 21 10 = 1 3 × 1 2 = 10 21 × 9 2 = 5 7 × 3 1 = 1 6 = 15 7 = 2 1 7
- 31. Classwork and Homework Classwork pages 34 and 35 Homework pages 43 If you are finished, come get worksheets from me