If the rifle will be used for plinking, which I think it would be, then I think you want a LOW powered spring or SSP rifle. Low power spring rifles are also MUCH easier to shoot than the high velocity rifles, less vibration and less sensitive to variations in hold. Because, if your kids can't hit what they are aiming at, the high powered rifles are WORTHLESS, as they will get frustrated and not want to shoot. This is why I recommend a LOW power rifle as the first rifle for a kid.
My 3 low power plinkers are the Daisy 953, the Gamo Delta and the IZH-60/61.
The Gamo DELTA has a so-so trigger. But is easy to cock and shoot. I think the Delta has been replaced by the Recon, but it is still listed for sale at various sites.
The Daisy 953 is my favorite. As an SSP, there is NO shooting vibration, which makes it a lot easier to shoot accurately. BUT you have to deburr the trigger, the stock trigger has a very gritty pull, and you will be fighting the trigger, which is BAD for accurate shooting.
The IZH-60/61 "looks cool" and for kids, looks can be important. IZH is the most expensive of the 3, but it has the BEST trigger. The IZH-60 is a single shot, the IZH-61 is a repeater (you cock the spring and the rifle self loads). It is also the lightest, and because of that when you shoot, it vibrates the most. The IZH is the hardest of the 3 to mount a red-dot or scope on.
Whatever you get, I recommend that you get an inexpensive red-dot sight, it is much easier to aim with than the stock open sights. I have an inexpensive TASCO red-dot on all my plinkers and training rifles. I think it costs about $35 at Midway.
The red-dot has ZERO magnification, so you compensate with larger targets. Like shoot at cookies and animal crackers rather than asprin tablets.
The only negative about a red-dot is...you have to turn it OFF when you are done shooting. Or expect to replace the battery often, so get at least one spare battery.