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Year 7 Autumn 1 Lesson 12: Adding and subtracting fractions 2ObjectiveTo add and subtract fractions including mixed numbers with different denominators.AimThis lesson links back to the baguettes lesson as a context for adding the fractionsResourcesPowerpointKey words: Denominator, improper fraction, proper fraction.Settler: Numeracy Ninjas (max 10 mins)Activity 1: In books:Students convert the ‘bogus’ mixed numbers into actual mixed numbers. This builds on work done last lesson and should be used again later this lesson.Questions for progressionWhy are these ‘bogus’ mixed numbers?What is the structure of a mixed number (‘integer + proper fraction’)What is wrong with this number? How can you change it?Activity 2: Link back to the baguettes lesson. Show the two different ways of sharing out the baguettes. This results in ? + 1/10 = 3/5.How can we show this?It is important to emphasise here that fraction pieces must be the same size to add together.Go through the thought processes, asking students each step of the way. This will be revision for some, but not for others.Students then answer the questions on slide 11 in their books.Bring class back together to mark answers.Ensure anyone who has mistakes corrects as they go along.Questions for progressionWhy are we splitting into this many pieces?What else could we split it into? Why do we choose the smallest number?Is we make the denominator 10, what must the numerator be?Can you think about equivalent fractions to help you?What must be true for equivalent fractions?What have the numerator and denominator be multiplied by in this case?Activity 3: Give students two minutes to think on their own about how they would answer the question on the board (mixed number + proper fraction). Some may struggle with this, so after one minute, show the diagram as a hint. Don’t offer any other help at this stage.Show the methods by the two students on the slide. Give students 2 minutes to think about explanations in their pairs. Students should plan their response.Choose a pair at random to explain the reasoning behind each method.Questions for progressionCan you explain what student 1 was thinking?Can you explain what student 2 was thinking?Was your original method the same as either of these, or did you have a different method?Activity 4: Give students two minutes to think on their own about how they would answer the question on the board (mixed number + proper fraction). Some may struggle with this, so after one minute, show the diagram as a hint. Don’t offer any other help at this stage.Show the methods by the two students on the slide. Give students 2 minutes to think about explanations in their pairs. Students should plan their response.Choose a pair at random to explain the reasoning behind each method.Students then answer the questions from the bottom of the slide in their books. There are extra questions on the last slide for anyone who finishes really quickly.Bring class together to go over answers, with students marking and correcting each other’s workRepeat for next two slidesQuestions for progressionCan you explain what student 1 was thinking?Can you explain what student 2 was thinking?Was your original method the same as either of these, or did you have a different method?Acknowledgements:Slide 1 from Bruno ReddyBaguettes from Multiplicative reasoning NCETMOther questions From Japanese textbook. ................
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