Thursday, August 6, 2009

Mini Abacuses

My husband uses a bead counter for gaming. He asked me to make him one to count into the 100's and this was the result. The other day, when it was out with his cards, I realized that it was a sort of mini-abacus. These little devices are great for kids, especially the ones who tend to be more visual-spatial and want to "experience" the numbers somehow. I can relate to the need to "experience numbers" but many parents and teachers have never felt this need and underestimate its impact for these kids. It certainly doesn't hurt other kinds of thinkers either.

Practical Use
We go eat a lot of potatoes in my house, so much so that I was thinking of buying larger quantities and putting them into a bin filled with sterilized sand to keep them fresh. However, I'd hate to have some getting really old at the bottom of the bin because I reloaded without realizing I still have some potatoes. A string of beads hung in the pantry nearby should be an easy way to keep track of the potatoes. But I probably want to know how to make these.

Building a Bead Counter
The only materials required are plastic pony beads (less than a penny each when bought in packs) and the cheapest polyester yarn you can find. These beads are nice because they are durable and uniform. I used double-thick yarn to string them. When the cheapest Red Heart brand yarn is doubled, it provides just the right amount of resistance for pony beads, keeping the beads in place but still easy to slide.

For a three-section bead counter, cut about 4 feet of yarn and fold it. If you have a needle that the yarn will go through, fantastic, if not glue (and allow to dry) or tape the ends to ease beading. Tie a knot an inch or so from the looped end and add ten beads to the doubled-up yarn. (The loop is great for hanging or attaching to something.) Leave about 2 inches of space before tying another knot or two. Repeat this action two more times so you have three sets of beads. Trim the end and you're done!

You can change the colors of the beads if you'd like, giving a new color for each place value. However, please do not use a mix of colors within each set of ten. Uniformity will simplify the use of these counters and lead to less confusion.

Alternatively, you can use yarn and pony beads to make something more like an abacus by making a sturdy wooden frame and threading the bead-strung yarn through it. (Just use double-thick yarn and plastic pony beads or experiment with other materials to get the right resistance.) This way you can use larger numbers or even decimals by assigning each row it's own place-value. If building a frame is not for you, try using small picture frames with the glass removed.

I'd write-up a little about using these counters but there is a lot of good information already out there. Peter Waycik's article on using the abacus in the classroom might give you some inspiration.