Symmetrical Semaphore
Problem
This is the semaphore alphabet:
Image by kind permission of http://scoutnet.org.uk/
Someone at the top of the hill sends a message to a friend in the valley. A person in the valley behind also sees the message being sent. They get the same message. What is it?
Are there any words that can make sense when viewed from the front and the back? We have found at least one!
(Dave wrote to say that in reality, at the beginning of every message the sender should send 'J', which is also the direction sign. This way the receiver knows which way round the message is and so can translate it correctly from front view or back view. Thank you, Dave.)
Getting Started
Which of the signals would look the same from the front and the
back?
Can you find pairs of signals that 'match' when seen from in front
or behind?
What about the order in which the signals are sent? Do they
matter?
Student Solutions
You answered this problem very well. Toby and Jodi from King's Park Primary School sent us the following:
First of all we decided which letters were symmetrical (D, R, U and N) and wrote these down. We then used these letters to make a word which we thought would be used in a semaphore message - RUN! We also made up the word - nun.
Some of you didn't pick up on the letter D being symmetrical. Remember, a person standing behind would still see just one flag up in the air. Rachael from Ardingly College, and Chris and Joseph from Moorfield Junior School, also found the word "urn" which, as Chris and Joseph pointed out, is an ancient Greek pot.
So that's three words in total. If you find any others, do email us.