Message to my Neighbour

Last week we had the problem below in our homework.  Today in class we tried to make them with interesting results.

Your best friend lives in the house next door to you.  Your bedroom window looks out on theirs.  You want to be able to get messages to each other without waking up your parents.

Design a system or machine to get messages to each other.

P.S. Your parents don’t let you take electronic devices to bed with you.

Our ideas were:

Cups and string

Did it work? 
A little bit but its not very reliable. What problems did we have?
The string got tangled very often.
It has to be very quiet and the string needs to be very tight. What would we change next time?
Use a hose.

Cups and hose

Did it work? 
Yes quite well. What problems did we have?
The hose was short.
Soft voices didn't travel as well. What would we change next time?
Make a bigger speaker or use bigger cups.

Pulleys and string

Did it work? 
Yes What problems did we have?
String gets tangled. What would we change next time?
Make the string tighter.
Strong anchor points.
Work on the stability.

Paper planes

Did it work? 
No (but one out of three got close) What problems did we have?
They are hard to throw accurately.
They would have trouble in the wind and rain.
What would we change next time?
Try and make more accurate planes.
Make them bigger so they can glide better.

Glue stick sliding on string

Did it work? 
Yes but only over a short distance.
What problems did we have?
It gets stuck in the middle.
What would we change next time?
Work out a way to get it higher.

White board pens on windows

Did it work? 
Yes it worked.
What problems did we have?
You have to write backwards.
You could not see the black whiteboard marker from a distance because it was not very clear. So I had to put a piece of paper behind the words so you could see it more clearly.
What would we change next time?
Use proper window markers to see if it make a difference.

As a class we think the pens on the windows is a good solution to the problem and it is pretty cheap and easy to set up.  
We think the hose and cups is also a good idea but a little harder to set up.  If you had the hose buried so it was permanently set up it would be an easy solution to use.