Q&A #19620

Safe-T Compass

T2T || FAQ || Ask T2T || Teachers' Lounge || Browse || Search || Thanks || About T2T

View entire discussion

From: Gail (for Teacher2Teacher Service)
Date: Jun 03, 2008 at 17:58:56
Subject: Re: Safe-T Compass

I use them in my classroom to do constructions.  You can draw circles and
swing arcs with them, much like you would with a regular compass, except
there is no chance of anyone getting poked, accidentally or on purpose.

When I first show them to my students, I let them tell me all of the details
they notice.  Then point out that the white circle can spin around.  In that
circle are a set of templates for making little circles.  To use them, just
place the compass on paper and hold the white circle and the arm of the
compass stable, and trace around the circles.

There are also some little holes in the white rotating circle.  They make
slightly larger circles.  To use them, hold the arm of the compass firmly
against the paper, and place the point of a sharp pencil in one of the holes.
Push the pencil gently and it will make the white circle rotate as it traces
a circle with the pencil point.

Finally, there are holes all along the edges of the arm.  Put a point on
your paper that you wish to be the center of the circle, and put the metal
grommet in the center of the while rotating circle right on that point that
you drew.  Put a finger on the grommet and hold it firmly against the paper,
so that it won't slide off.  Place the pencil point in one of the holes and
gently push it.  It will circle around and trace out the circumference of the
circle you are trying to draw.  I find it is best if you hold the grommet
with your left hand pointer finger, and cross your right arm in front of your
left arm.  Start drawing the circle in this crossed position, and proceed in
a clockwise direction, and your pencil point will travel all the way around
to end up under your left arm, and you won't have an arm in the way while you

For angle constructions, just place that grommet over the point you would
have fixed your compass on, and then select a hold to use to swing an arc.

It really isn't difficult, after you get the hang of it.  I hope this
helps...   :-)

 -Gail, for the T2T service

Post a public discussion message
Ask Teacher2Teacher a new question

[Privacy Policy] [Terms of Use]

Math Forum Home || The Math Library || Quick Reference || Math Forum Search

Teacher2Teacher - T2T ®
© 1994- Drexel University. All rights reserved.
The Math Forum is a research and educational enterprise of the Drexel School of Education.The Math Forum is a research and educational enterprise of the Drexel University School of Education.