# [blindkid] Questions about rulers and perpetual calendars

Richard Holloway rholloway at gopbc.org
Tue Nov 2 15:44:07 UTC 2010

```Interesting idea with the hot glue. With a wide enough ruler one could probably offset lines and make at least eights and here is a commercial 1/8 inch ruler as well (\$3.25):

http://www.maxiaids.com/products/1274/Tactile-Braille-Ruler.html?utm_source=Froogle&utm_medium=organic&utm_campaign=Froogle&idAff=15225

I guess in theory you could go quite fine with staggered sets of lines (16ths or probably 32nds with something like raised commercial printing which could be slightly tactile), but I think once you pass around 1/8th a child would need a really strong foundation in the concept because you end up with lines jumping in and out so they can be differentiated, or it will start to feel like a texture, not distinct lines or marks. (As far as "proper" braille and similar sized raised lines, once you get around 16th of an inch, you begin to raise the whole area and defeat the purpose, right?)

To be clear, I'm a total novice with this, trying myself to grasp these concepts as I anticipate Kendra's fairly near-term needs. RIght now, we're just doing second grade measuring in cm and I can already see this it is quite challenging to measure with accuracy. It is really easy for the ruler to shift a few mm and if "a few" is more than 5, one is probably going to assume the next number and get the problem wrong. Convert this to 16th's or mm, and how is it physically possible? Visually, for fine measurements one has to close one eye and sight down the side of things to avoid parallax errors. I get that there are no parallax problems with tactile rulers, but there are practical physical limits for precision. Teachers need to work within these limits and modify the assignments if appropriate.

On Nov 2, 2010, at 11:13 AM, Sally Thomas wrote:

> I'll be interested to hear about the ruler.  I have not found anything that measures less than 1/4".  I did make a tactile ruler with hot glue and a wooden ruler.  The hot glue stays on really well.
>
> Sally Thomas
> ----- Original Message ----- From: "Wendy Molle" <wmolle at schoharie.k12.ny.us>
> To: <blindkid at nfbnet.org>
> Sent: Tuesday, November 02, 2010 9:37 AM
> Subject: [blindkid] Questions about rulers and perpetual calendars
>
>
>> Hi!
>>   As part of our 4th grade math curriculum, our students need to use rulers that go down to 16ths of an inch AND perpetual calendars.  Does anyone know where we can locate Braille versions of these?
>>    We and our TVI have not been able to find anything.  We tried to make a ruler, but with no success.  When we tried to type in the perpetual calendar to emboss it, it got all garbled and unusable.  Although I am sure it could be sorted out, it would be very time-consuming.  We are hoping that someone knows where we can purchase one.
>> Wendy Molle
>> Schoharie Elementary
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