Over the last few weeks The New Scientist has been running a series of articles written by Hanna Joshua covering low cost projects featuring the MicroBit and sometimes a Pi. The series is graduated in difficulty with the first few aimed at making people comfortable with wiring up batteries and components. Well worth keeping an eye on this. Each project is covered by a short how-to, with a list of required parts. With a little help most 8+ children will find these to be stimulating holiday projects and some could be readily adapted into something either interesting or useful.
The first dozen projects can be found at New Scientist