To practise extended and half stitches, you can use any yarn you like and a hook in a suitable size for the yarn – whatever you feel most comfortable with. We used DK cotton yarn and a 4mm hook.
Start your practice piece with a couple of rows of treble stitches to give the fabric a sturdy foundation – it will also give you a base row of ‘normal’ stitches to compare against your extended stitches. We worked 13 tr for two rows (ch15, tr in 4th ch from hook and in each ch to end, turn, ch3, tr in each tr across, turn).