I created this pattern to offer my grandaughter as something that was interesting, not very large and only needed knowing how to make chains and double crochets (US- single crochets).
In the event she preferred the idea of using her multi-coloured yarn to make a scarf but I have now created a tutorial showing how to make what I call
A Beginner Coaster
This needs three different coloured yarns. Cotton gives the most attractive finish I think, but acrylic or similar would work as well.
I use the fact that using just three colours you can create a stripped pattern without having to cut the yarn and have lots of ends to sew in.
I used a DK weight yarn (US – light worsted) and a 4mm crochet hook. The size of hook could be adjusted up or down if you feel more comfortable with another size.
(There are word only versions of the pattern in UK & US terms at the end of the post.)
Start with a slip knot 
The reason I show you a photograph is that a slip knot can end up two different ways and if you make it like this it is possible to pull the free end to make the loop smaller when you have finished. (This is useful to know if you start casting on for knitting with a slip knot too).
You then make 20 chains. 
Now we will add the second coloured yarn.
I like to tie the new yarn to the old as you can then pull it without it coming loose. (I normally untie the knot before sewing in the ends.) 
Using the new yarn, make another chain. 
When working rows of double crochets, (US – single crochets) each row starts with what is called a ‘turning chain’ that gives a bit of height before working the first double crochet. (US – single crochet)
There are four different ways to work into the starting chain but the easiest way for beginners is to turn the chain so you can see the front and insert the hook under the top loop of each chain in turn. 
The needle shows where to insert the hook for the first stitch. This is the twentieth chain from the start.
Work a double crochet (US – single crochet) into this loop and each subsequent loop. Here you can see the first three.
And here you are, having pulled the yarn through the last chain and about to complete the stitch. 
This is when you attach the third coloured yarn, in the same way as before, prior to completing the stitch with the new colour. 
Now make a turning chain. 
And turn you work to start back along the row.
The first double crochet (US – single crochet) is worked into the second loop from the hook which is easily found as it is the first loop in the previous colour. 
Continue with a double crochets (US – single crochets) into each subsequent stitch from the previous row. 
Complete the last stitch with the first colour which you will find waiting for you. (You should have made exactly twenty).
After this you continue working each row as just shown, picking up the coloured yarn that you find at the end for the last stitch, until you have made twenty rows.
The last row (the twenty-first) will be made with the first colour and this time you will make three stitches into the last, twentieth, stitch. 
This will be the first part of the edging.
You now work your double crochets (US – single crochets) into the first gaps down the side. These gaps will either be after a starting chain or the last dc of a row.
Starting with working into the row two away from the edge. 
When you get to the last row, you start to work into the other half of the starting chain.
Each chain has three loops , so you will be working under two loops this time.
Here you can see I have inserted a needle under the first and last places you will be working.
You work two stitches into the place on the right and then one into each subsequent chain.
You now work two more stitches into the side of the first (in this case the pale pink) row.
You then continue up the second side as before, ending in the last row which is where you started the edge, and work two stitches here as shown in this photograph.
You should have twenty stitches on each side plus an extra one in each corner.
(But unless you are a perfectionist, it won’t really matter too much if you are one out anywhere.)
Now all you have to do is cut toff the yarn and sew in the ends. There will only be six.
I will now show you how I would do this.
Finishing off
I like to finish off the final end of yarn as invisibly as possible and so I pull out the last loop until it is really long. 
So I can cut it where the hook is and still have enough yarn to sew in the end.
I then attach a needle and thread the needle two loops away as in this picture. 
You are going to make a loop that will substitute for the loop of the first stitch.
Pull the yarn through and thread the needle back where the yarn came from.
Pull the yarn till the loop matches the others. 
Now sew in all the ends.
I turn the work to the other side and I will show you just how I do one end.
I untie the knot that held the yarns together (but you can leave out this step if it feels too tricky) and slip the needle under a few loops of the same colour along the row. 
I pull the needle through and then insert it under some of the same loops in the opposite direction. 
Of course it is important not to insert the needle in the same place it came out from or you may simply pull the yarn out again.
I find this double direction approach is especially good for things like blankets to stop the ends coming loose.
To finish: here are a couple of coasters I made while developing the pattern, so don’t count the stitches but see the variety. 
Now the word only pattern.
Pattern (UK version)
Start with 20 chain in your first colour then tie in the second colour and pull through to make another chain. This will be your ‘turning chain’.
Row 1: Insert hook into upper loop of starting chain, two loops from hook and work a dc into this and each subsequent chain. Complete the last dc by tying in the third colour and using it to complete the last dc. Make 1 ch in the new colour and turn work.
Row 2: Work 1 dc into each dc of the previous row, completing the last dc with the coloured yarn you will find at the end. (20dcs). Make 1ch and turn work.
Rows 3 – 20: Repeat Row 2.
Edging
Top Row: Work 1 dc into each dc of the previous row, adding two more dcs into the last stitch. (Giving three in total in the last stitch.)
Left side:Starting two rows down, work a dc into the side of each row.
Bottom: Work 2 dcs into the first of the starting chains, then 1 dc into the other 19.
Right side: Work 2 dc into the side of what was the first row and 1 dc into each subsequent row. Work an extra dc into the last row which is where you started the edging.
Cut the yarn and sew in the ends.
Pattern (US version)
Start with 20 chain in your first colour then tie in the second colour and pull through to make another chain. This will be your ‘turning chain’.
Row 1: Insert hook into upper loop of starting chain, two loops from hook and work a sc into this and each subsequent chain. Complete the last sc by tying in the third colour and using it to complete the last sc. Make 1 ch in the new colour and turn work.
Row 2: Work 1 sc into each sc of the previous row, completing the last sc with the coloured yarn you will find at the end. (20scs). Make 1ch and turn work.
Rows 3 – 20: Repeat Row 2.
Edging
Top Row: Work 1 sc into each sc of the previous row, adding two more scs into the last stitch. (Giving three in total in the last stitch.)
Left side:Starting two rows down, work a sc into the side of each row.
Bottom: Work 2 scs into the first of the starting chains, then 1 sc into the other 19.
Right side: Work 2 sc into the side of what was the first row and 1 sc into each subsequent row. Work an extra sc into the last row which is where you started the edging.
Cut the yarn and sew in the ends.
