You will be happy to see your cutie pie’s attention span is improving positively day by day. Also, he has lengthened the time, where he stays engaged in an activity. You can also improve his attention span by involving him more in small activities, and definitely these minor steps can him to build a better concentration in future.
What you can do
The most important thing in parenting is if you give attention you will get attention. If you will hear your child patiently, then he will give the same amount of attention in response, as he observes and copies you. This simple thing will really improve his attention.
Also, you can introduce Puzzles, Board Game (ludo, monopoly or word scrabble) and treasure hunt to him, which can happily engage him for quite some time. The main thing you need to work on is let him focus on one task at a time and you need to strictly stick to this, as it will improve his focus power. Also you can play simple memory games with him it can be related to his syllabus as well. Finally as parent, you can set up a reward system as it can motivate your child to stay on task and will likely to improve his attention.