For me, the problem with a 1x scope is that at 50 yards or even 25, it might be difficult to see hits on paper (depending on type of paper target). I find a 3-9x scope ideal. As a shooter it is motivating and fun to see instant validation on a hit. But going this route it is very important you need to make sure the eye relief is set up for him, as mentioned in one earlier post.
If shooting reactive targets like steel or clay pigeons (on a berm), then a 1x will be ok. Depending on how fast he learns, he can outgrow a 1x quick and yearn for pinpoint accuracy which is fun.
Since you already have a 1x I guess use it first then when he outgrows it consider a 3-9x or similar. Nikon rimfire scopes were great but they are long discontinued; I have one on a basic 10/22 and used those see-through rings that allow you to use the iron sights. I have an Athlon 3-18x on my Tikka rimfire bolt gun and my kids have a blast using it up to 300 yards on steel. I also have 10/22 backpacker takedown and is purely iron sights.
If shooting reactive targets like steel or clay pigeons (on a berm), then a 1x will be ok. Depending on how fast he learns, he can outgrow a 1x quick and yearn for pinpoint accuracy which is fun.
Since you already have a 1x I guess use it first then when he outgrows it consider a 3-9x or similar. Nikon rimfire scopes were great but they are long discontinued; I have one on a basic 10/22 and used those see-through rings that allow you to use the iron sights. I have an Athlon 3-18x on my Tikka rimfire bolt gun and my kids have a blast using it up to 300 yards on steel. I also have 10/22 backpacker takedown and is purely iron sights.