While a lot of the statements in this thread could be true in some circumstances, I think there is some misinformation here, especially as it would pertain to guiding a beginner.
Generally, the individual string sections do not play in chords, or divided (hence the term divisii). To form chords, the strings usually play individual lines that fall into the general ranges, high to low, of soprano, alto, tenor and bass, corresponding to 1st violins, 2nd violins, violas and cellos respectively. The double bass, if used at all, provides extra foundation either by doubling the cello line or independently.
The difficulty with dividing strings is that the sections are formed to be in balance with each other. Thus dividing one section and not others weakens that balance. One difficulty in the example in the previous post is taking the smallest section and dividing it where the violins are massed in octaves on the melody/soprano. Both violins on the melody would duplicate and wipe out the higher viola part, and there would be very little carrying power in the alto, with the cello forced to take the tenor. The bass becomes particularly problematic in that, if it is sounding C3, it is in a very high, less favorable part of its register. But the bass sounds an octave lower than written, so if it is actually sounding C2, then the distance between it and the cellos exceeds an octave and is really too far to balance the chord well. In fact, the chord itself is outlined in closed voicing where and open one, vc = C2, va = G2, vn2 = E3, vn1 = C4 might be better (although the viola is a little low in its range, yet on the least functional note of the chord). Another weakness overlooks the fact that we tend to hear the outer voices, soprano and bass, more than the inner ones. So doubling the violins in octaves is not so much for strength (we’ll hear the melody just fine) as it is for color. Perhaps a different solution, if dividing a section was desirable, would be to have the second violins play the alto, violas on tenor and cellos on the bass, either doubled by (as the name implies) the double basses, and then divide the first violins in octaves on the melody. Obviously, I’m picking on the example a bit (and trust Hetoreyn that you will take it as constructive good cheer). In all fairness, the inclusion of winds (and brass) could balance his example just fine. The point is – especially in the beginning – to understand and write consistently for the strings as a section unto itself. Then as more experienced is gained, branch into more creative things relying on the strong foundation built earlier.