Danny Dunn, Time Traveler

I read a bunch of these as a kid but I don't think I read this one.
For books aimed at 8 year olds, the time traveling parts are a little complicated.
A character gets duplicated because a past version meets a future version.
There is also discussion of alternate timelines.
The kids learn a little history and electricity by meeting a famous person in the past.
These are fun short adventures long out of print.
But you can sometimes find them in used bookstore or shops.
And it's possible there are digital copies out somewhere on the web.