Maths - Lessons with Grandpa
What the lesson is about
Students often choose to interpret questions in ways that differ greatly from those imagined by the question-setter. Take this problem on sequences: Grandma gives Henry pound;5 on his third birthday and then increases this amount by pound;2 for each subsequent birthday, writes Jonny Griffiths.
This is about arithmetic sequences, but what are my students thinking? I could see little appreciation of the mathematics of the situation. The word that had captured them was "Grandma". For each of my students, that word was summoning up pictures of their own grandmothers.
But then the question goes on to embrace Grandpa: Grandpa gives Henry pound;5 on his first birthday and then increases this amount by 10 per cent for each subsequent birthday.
The human aspect began to take over the lesson. Have Grandma and Grandpa conferred about their gifts? Does the separateness of their giving reflect some deep division in their marriage? Once the first few terms of Grandpa's giving are calculated, it is agreed that he is a bit odd: pound;5, pound;5.50, pound;6.05, pound;6.66, pound;7.32 .
I did my best to drag the class back to the question. On which birthday does the total amount received by Henry from Grandma first exceed pound;650? The answer turned out to be the 26th.
"My grandparents disowned me when I was 15!" cried Daniel.
I am all for real-life problems appearing in the classrooms. However, the above question is "real", yet strangely unreal, which led to my students being distracted from the maths.
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