At the moment I am churning out blanket squares for Japan (For anyone in the UK who is interested, details can be found on the London UK Ravellers group on ravelry.)
It occurred to me to offer some hints for those teaching beginner knitters. One of the first things I ever knitted as a child was a blanket square for Biafra.
There are lots of ways of making squares and any experienced knitter probably has their own favourite, but this is the easiest for beginners. It requires the ability to make a slip stich and put it on the needle, to make a knit stitch, and to make a single increase (of any kind) and a single decrease (of any kind) at the start of a row. It does not need any particular tension or even a tension that stays the same. And it can be done in any yarn.
To start, make a slip knot and put it on the needle.
From this point every row is: increase 1 stitch (by any method), knit to the end of the row.
Continue until the side edge is the required length. Beginners (especially children) tend to pull their knitting out as far as it will go when measuring so it may be a good idea to suggest a measurement slightly larger than the one you actually want!
When the required point is reached, break the yarn leaving a long tail, and knot it together with a new yarn close to the end of the row. I suggest this because having one colour for the increases and a different colour for the decreases means beginners are less likely to get muddled as to which they should be doing. Also it makes the blankets look good when sewn up.
From this point, every row is decrease one stitch (by any method) and knit all the stitches to the end of the row.
When only one stitch is left, cut the yarn leaving a long tail and pass it through the stitch left on the needle (in any direction).
It is a good idea to show beginners that the two sides of the square will not be exactly the same in the middle. Otherwise they may think they have made a mistake.
When sewn together as a blanket this difference is not noticable.