All the tiles should become one single chain. Where two tiles touch, both halves have the same number of dots.
First look for a tile that only fits on one side. The chain starts or ends with it.
A tile may be turned around. The letters under the tiles spell a word in chain order. If no word comes out, the chain is not right yet.
Example
For parents
What does this exercise practice?
Building the chain practices careful comparison and planning ahead, because every tile laid decides the next one.
Common pitfalls
Children often start with any tile and end up with one left over. Then it helps to start again at an end where only one tile fits.
How to practice at home
Pick five real domino tiles that make a chain, mix them up and let your child build the chain again.