Bests & Worsts Reviews from Amazon

I bought the abacus for my seven year old boy-girl twins to help them with their adding and subtracting. This particular abacus has two faults: 1. the ten beads in each row are identical in color. The abacus I remember using as a kid had the five beads on the left side of one row one color and the five beads on the right of the same row a different color. This makes a world of difference when sliding over various amounts. For example, lets say you want to slide across seventeen beads in total. If each row had five beads on the left in one color and the other five beads in the same row a different color, then you would easily slide across a complete row of ten in the first row, an easily identifiable 5 beads in the second row (same color), and then an additional two more beads in the second row to make seventeen. With the Melissa and Doug Abacus, you would have to slide across a full row of ten beads in the top row, and then count up seven beads (all the same color)in the second row and slide them over. 2. The abacus is narrow. If you slide ten beads over to the opposite side, they don't all go past the last bead in the next row. This abacus would be so much better if it was about 5 inches wider. The abacus that I prefer is Desktop Abacus by Learning Resources Desktop Abacus The desktop abacus by Learning Resources has the features that I wanted.