Salam.

Last night I conducted a tutorial on mathematics. Topic Geometric Progression Series.

Consider 1, 1/2, 1/4,1/8, ….

where a = the first term = 1
and the r = the common ratio = 1/2

the students are asked to find the T8 the eighth term.

Of course they have the formula T8 = ar ^ 8-1

= 1 (1/2) ^ 7
= 1 / (2^7)

approximately 0. Yes zero.

Then I asked one of the girls. What is ‘r’? she answered it as half which was perfectly correct. Then I moved to the second and the third terms in the series. I asked her again . What is ‘r’?

She said ‘something between 1/2 and 1/4’. Again I probed … so what is ‘r’?

2. Now her nose started to sweat. Few drops of water came down from the upper part of her fore head. What is ‘r’?

Something between half and that quarter. (shakingly holding her pen)

I asked her many times about ‘r’.

Conclusion: using a formula is completely different from getting the real understanding of what we meant about something in particular. This time I called it ‘r’ the common ratio in a geometric progression series.

I just wonder where I commited the wrong in my teaching. I had this topic on for the last 2 weeks.

Basically, this girl is confuse with two things. the first term and the next term with ‘r’ as the multiplier.

T2 = second term = a(r) = 1(1/2) = 1/2

Any body can help please? TQ.

wasallam.
regards.

dr sazali DIT1103 maths IT 1

Original link: https://nenez9595.blogspot.com/2010/09/big-challenge-teaching-weaker-set-of.html