A really good time to recognise that your DC's need to build their independence and ability to focus at times without adult intervention. This can be built with an obvious eye on keeping your children safe. Using the good ideas on here, let you DC's try them out, provide the resources and some ideas then let them play whilst you are busy with something else alongside.
If they can't focus for long, add a question, another small resource, an idea to support them - but don't get overly involved. If they can't focus for long, this is something to really work at overtime and of course time related to their age.
What do your children really like to do? What are their interests. Children will focus for longer on something they have chosen and re keen on, rather than something imposed. Once they are interested and playing actively, don't distract, let them continue, keep the same thing going, listen to them, add to their play or join in for a minute or two.
Children need to play, to be resilient, to work things out for themselves, to try and fail, to be creative and imaginative. The 'Characteristics of Effective Learning' explain in more detail and support learning for children 0-5 years.( Early Years Foundation Stage Curriculum).
It is really detrimental to children's later learning if these are not on place.