LEARNING ADVANTAGEDemonstration Compass - For Use on Chalkboards and Whiteboards - Teacher Aid for Geometry, Design, Art - Classroom Supplies

When you need a large circle this product cant be beat.

Useful for general circles, but if you want something precise this is NOT the tool for you.

I was at first delighted to see a large demo compass that I could use on the white board at school. My students are doing geometric constructions and I thought it would be great to be able to walk the whole class through them at once. First I tried the suction cup center point: FAIL!!! The pivoting ball doesn't stay aligned in the suction cup and it is impossible to get a perfect accurate circle. I switched to the rubber tip. Again: FAIL!!! The rubber tip slips on the white board and if I apply more pressure it then has a similar problem to the suction cup: the point doesn't remain stable. There is also nothing to stabilize the radius setting, so getting a perfect demonstration circle with this instrument is literally impossible. I've resorted to free-handing it just to give my students the general idea. It's almost as good doing it that way as trying to get a circle out of this compass. I'd have given it no stars, but that isn't an option.

Bought this to teach constructions in Geometry. I wish it were about half the length. The parts also fall off easily. It's just too bulky to really work well.

Worked great for what I needed.

As a home-schooling parent, I thought this would help me to demonstrate geometric constructions (as it physically resembles a typical student compass more so than some white board compasses I've seen). Though usable, it takes a bit of practice. Even then it requires focus and care to make circles or arcs -- it's all too easy to change the angle of incidence while using the thing and thereby change the effective radius (meaning what you end up with is not circular). This is exacerbated by the pivot attaching the suction to the rest of the compass, which rotates freely as it should but also quite freely changes its tilt with respect to the whiteboard. I imagine if I were using in front of a class of students sitting many feet away, the practice and intentionality of movement required would be worth it. But for my daughter who is only a few feet away from our 4' x 6' whiteboard, it may not be worth it: I might just as well sit next to her with paper and student compass in hand and demonstrate that way!

The compass legs are so flexible that you can not make an accurate circle. It needs rigidity to be useful. Very hard to demonstrate concepts to my students if I can not draw accurate circles and arcs for constructions.

The plastic this is made of is flimsy, and it does not maintain suction well. Not worth 20 dollars.