Ascending order mix of decimals and fractions
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parent2013
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- Joined: Mon Aug 12, 2013 10:13 am
Re: Ascending order mix of decimals and fractions
I suggest the approach will depend on the exam
CEM (try to do mental calculation, speed is the key)
4/5 is 0.8: child should remember this by heart
5/8:
Option 1: long division which may take 15-25 seconds.
Option 2: 5/8 > 4/8 (0.5) and 5/8 is < 6/8 (which is 3/4 i.e. 0.75)... therefore smallest.
Olave's/Wilson/Sutton (show workings)
Compare using decimals as it requires not changing the first number and 2nd fraction is standard one.
0.85 (no change required)
4/5 = 0.8
5/8: Show long division workings and it is 0.62 i.e. smallest.
CEM (try to do mental calculation, speed is the key)
4/5 is 0.8: child should remember this by heart
5/8:
Option 1: long division which may take 15-25 seconds.
Option 2: 5/8 > 4/8 (0.5) and 5/8 is < 6/8 (which is 3/4 i.e. 0.75)... therefore smallest.
Olave's/Wilson/Sutton (show workings)
Compare using decimals as it requires not changing the first number and 2nd fraction is standard one.
0.85 (no change required)
4/5 = 0.8
5/8: Show long division workings and it is 0.62 i.e. smallest.
Re: Ascending order mix of decimals and fractions
Actually it's 0.625parent2013 wrote:
5/8: Show long division workings and it is 0.62 i.e. smallest.
May make a difference, depending on how close the items listed are.Something like "two-eighths = 25% = 0.25"" should be quite easy to memorise and may save a bit of long division. (Or even, just drilling that 1/8 = 12.5%?).
Outside of a dog, a book is a man's best friend. Inside of a dog it's too dark to read.Groucho Marx
Re: Ascending order mix of decimals and fractions
Yes they should know that 2/8 = 1/4 = 25% = 0.25.ToadMum wrote:Actually it's 0.625parent2013 wrote:
5/8: Show long division workings and it is 0.62 i.e. smallest.
Something like "two-eighths = 25% = 0.25"" should be quite easy to memorise and may save a bit of long division. (Or even, just drilling that 1/8 = 12.5%?).
It should then make sense that 1/8 is a half of this i.e. 12.5%.
And if they need to find 5/8 as an exact decimal I think it is quicker and easier to think of it as 4/8 + 1/8.
i.e. 50% + 12.5% = 62.5% = 0.625
Rather than having to work out 5 / 8 as a long division.
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parent2013
- Posts: 452
- Joined: Mon Aug 12, 2013 10:13 am
Re: Ascending order mix of decimals and fractions
Calculating up to 3dp is required if the numbers are very close. In this instance only 1 dp would do i.e. 0.6 is lesser than 0.8. There's no need to calculate up to 0.62 or 0.625.
A good approach is to remember fractions & decimal relation for common ones but don't be surprised if the child crumbles under the exam environment and makes silly mistake by assuming that 5/8 is 0.75 and not 0.625. So, be very very sure on mental calcs otherwise calculate (this is what I taught to my ds) - couple of seconds slower but safer/accurate option.
The other point I'm trying to make is to demonstrate workings (specifically for super-selectives) as they want to filter out children who can show the steps/approach performed to come up with the answer rather than mental calculation. Here are the sample instructions:
MGS - For each question, show all your working in full, as this will be marked, and then write your answer clearly in the space provided.
St O - Show your workings in the space provided with each question.
MT - You should show all your working on this question paper.
SO - Show all your working. You may be awarded marks for correct working even if your final answer is incorrect, and a correct answer unsupported by correct working may not receive full marks.
A good approach is to remember fractions & decimal relation for common ones but don't be surprised if the child crumbles under the exam environment and makes silly mistake by assuming that 5/8 is 0.75 and not 0.625. So, be very very sure on mental calcs otherwise calculate (this is what I taught to my ds) - couple of seconds slower but safer/accurate option.
The other point I'm trying to make is to demonstrate workings (specifically for super-selectives) as they want to filter out children who can show the steps/approach performed to come up with the answer rather than mental calculation. Here are the sample instructions:
MGS - For each question, show all your working in full, as this will be marked, and then write your answer clearly in the space provided.
St O - Show your workings in the space provided with each question.
MT - You should show all your working on this question paper.
SO - Show all your working. You may be awarded marks for correct working even if your final answer is incorrect, and a correct answer unsupported by correct working may not receive full marks.
