DS1 is just finishing yr1 and got a very good report, but his handwriting has been identified as an area that needs work. He can form his letters correctly but he's very slap-dash, he does it as quickly as possible and sometimes they end up with tails facing the wrong way. The letters are often varying sizes and not on the line. He scored beyond expectations for his sentence construction, spelling etc, it is how he writes rather than what he writes that is an issue.
Any tips for helping him improve over the summer without it being really dull?