Best Geometry Compass for High School Students

Students have purchased a wide variety of compasses for my geometry classes across the years; some good, some terrible, and one that is really excellent.  I've put together a summary of the pros and cons of each type of compass but please focus on my favorite: the Circle Master Compass from Academic Industries Mathtools Inc. It's the greatest I recommend you try it out.

Before I go on and on about why I love the Circle Master, here's a summary of what I think's good and bad about the other common compasses:

Plastic Pencil Locking Wheel
This is probably the least durable compass, in my experience.  

Pros

• inexpensive - often around $1
• golf pencil can be replaced

Cons

• plastic wheel holding the pencil steady breaks quickly
• hinge at the top cannot be tightened and it gets loose easily
• barely survives one lesson let alone a school year
• point is unprotected so you may get poked 

Pencil with Metal  Flap
Only slightly preferable to the above model.

Pros

• inexpensive - often less than $1
• golf pencil can be replaced

Cons

• metal pencil flap only fits some golf pencils
• hinge at the top cannot be tightened and it gets loose easily
• metal tends to be brittle so parts sometimes snap
• often only survives a few lessons
• point is unprotected so you may get poked 

Pencil with Plastic Flap
I want to love this one but it just wears out.

Pros

• Inexpensive - often less than $3
• golf pencil can be replaces
• many models can be tightened at the top hinge (if you have a tiny screwdriver)

Cons

• plastic flap is breakable and cannot be tightened
• not all golf pencils fit snugly
• often survives the whole year but accuracy steadily declines  
• point is unprotected so you may get poked  

Compass with Locking Wheel
Great accuracy but...
Pros

• locking wheel ensures accuracy isn't lost during use
• durable 

Cons

• relatively expensive - ranges from $8 to over $20
• the graphite is a chunk that is held in place by a tiny wheel - the graphite gets lost
• locking wheel may make use more time consuming 
• point is unprotected so you may get poked 

Circle Master Compass
Get this one!!!   

Pros

• inexpensive - $2 - $2.50 each depending on quantity
• durable - no plastic parts - My students used them for the first time this year and we had ZERO breakages.
• accurate - the adjustable thumb wheel in the center is easy to tighten and loosen as needed
• retractable - the second photo shows how you can retract the points to make it safer
• uses a full size pencil - They all fit, you can even use a pencil with an eraser!

Cons

• Students may not understand how to use it on the first try
• On first use, the thumb wheel may be too tight to turn by hand
• Must be ordered online - or stocked in your school bookstore

My school bookstore will only be stocking these compasses next year.  Well over 100 students used them throughout this school year and we had no problems with accuracy or breakage.

If you go to www.aimathtools.com to check these out, I also recommend the Geometer and Press-On Graph labels.  They're awesome too!

Thank you for reading and in case anyone is wondering, no, I have no affiliation with Academic Industries Mathtools Inc aside from the fact that I love some of their products.