Colour work blocks, or Intarsia, is a method of working solid blobs of colour in the middle of the work. Rather than standing the yarn, like fair isle, each panel of colour is worked from a separate ball, and the strands of yarn are twisted at the colour change to secure them. Take the first colour yarn and knit the required number of stitches. At the colour change hold the first colour to the left and pick up the next colour from underneath to twist them. Repeat this for every colour change on the knit side of the work. On the purl side, the technique is exactly the same. Work to the colour change and, holding the working yarn to the left, pick up the next colour from underneath and purl over the top to secure the strands. It is usually easier to work this technique using small bobbins of yarn, rather than a whole ball, to avoid tangles.