Some coins were arranged in a row.
Half of them were tails up.
Two of the coins are turned over and now one third of them are tails up.
How many coins were in the row?

Teacher: Here is a visual aid to use if required. Coins can be dragged and, to turn them over, doubleclick.

Have a guess!

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Topics: Starter | Fractions | Problem Solving | Puzzles

• Mrs A Milton, Ysgol Ardudwy
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• I have used your starters for 3 years now and would not have a lesson without one! Fantastic way to engage the pupils at the start of a lesson.
• The Best Maths Group Ever 7cd/M2, King Alfred's College, Oxfordshire
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• Some of us caught on quickly. But majority found it tricky. Drawing coins helped to explain the answer.
• Rachel, Claverham
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• You should have been more specific with the wording and said that the tails were turned over.
• Francis, Halifax
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• The wording of the question is fine. If 1/2 of the coins start as tails up, and, when 2 are turned this becomes 1/3, it should be obvious that it was tails that were turned because 1/3 is less than 1/2.
• Gabriel, Edgware
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• The wording is a problem...
If you started with 6 coins and turned one head and one tail over, you would get to 1/2 and 1/3.
Surely?
• Primary 7, Bargeddie Primary School
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• The majority of our class found this very confusing at first. However, Lewis in our class worked out the answer very quickly: he worked out that if he thought of a number on the 2 times table, and tried to take 2 away to see if it was on the three times table then he would have his answer...
The rest of the class were most impressed!
• Nick, Weston
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• This was epic.
• Sarah, Tenbury
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• I think your algebraic answer is harder than it needs to be. if you say
x/2 - 2 = x/3 (+2 and -x/3 on both sides then

x/2 - x/3 = 2 (x6 both sides)
3x - 2x = 12 so x=12.
• Mr Miller, Brough Primary
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• One child in our class found this particularly confusing but she eventually understood after much discussion and debate with the teacher!
Everybody else found it interesting, if not challenging.
• Holly Walton, Calmore Junior School
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• Really good website.
• Matthew Zhao, 5S, Craigslea State Primary School
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• Challenging for average grade 5s, although very easy for my intelligent brain and my quick way of using Trial and Error. =).

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This starter has scored a mean of 3.0 out of 5 based on 485 votes.

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