Solving exercises from books is one of the best ways to train the skill of finding the best move. But for many children, consistent book work may not be as realistic as solving problems on the computer. Fair enough! This is why Alex and I have meticulously entered Steps problems into chessbase, to be able to assign them on our online platform as HW. New Steps classes start this coming week - all the information is here: https://masterchess.org/collections/all
There are other electronic resources I wanted to draw to your attention as well.
Chessity is a website I have used with my own students for many years. I think I was the first mass adopter among American coaches. I remember my contact at Chessity telling Elizabeth Spiegel that 'my students are very fanatic'. Nice words for a coach to hear! Chessity is a Dutch site, with a lot of philosophical and curricular similarities to the Steps. They have fundamental lessons, produced in an engaging way that takes advantage of the online format, and a rich database of online problems. One of the best ways to use Chessity is the following:
Create an account. (Make sure simple mode is disabled, if the student is a non-beginner). Beginners should simply go through the basic lessons, trying to get 3 stars on every lesson. Tournament players can make use of the "training" feature. This is probably my favorite thing about Chessity! Training has three settings: Easy, Medium, and Hard. For most children, including consistent tournament players, easy is not actually that easy! Whichever you select, it opens a game where you have to get 9 questions right without getting 3 questions wrong. The positions are tactical in nature, and an excellent reflection of the tasks students face in real games: They may have to defend against a mate threat, win material, find a mating combination, find an only move to preserve material equality, etc.
One thing I really like about Chessity Training is that it rewards accuracy, rather than speed. Students can spend as much time as they want on problems, trying to get the right answer on their first (and only!) try. This reflects the conditions of a real game, in which most students tend to play far too quickly and make regular blunders as a result. I remember once I went out of town for a couple weeks, and came back to see that a promising student was suddenly calculating precisely in 3 and 4 move bursts. I asked her what she did - "I was on Chessity for a long time every day during break!"
The chess.com tactics trainer is another huge source of exercises. Some of the problems feel quite computer generated to me, but I know many children have successfully used it as part of their solving routine. Lichess has a superb interface and their own tactics trainer, but I don't know enough about it to say anything about it. I imagine it is another useful source! Chesstempo is another site I don't use myself, but many strong tournament players and students alike give it positive reviews.
A couple more things I should mention: First of all, Combinative Motifs exists in download form! Google CT-ART and download the latest version. (It costs money, but it's worth it). Even if a child is already going through the book Combinative Motifs, this is an excellent way to review. If they are not going through Combinative Motifs, then CT-Art will be an incredible source of tactical pattern recognition.
Finally, chessable has put multiple tactics books on their website, taking advantage of their 'spaced repetition' formula. For students who enjoy this format, check out the Woodpecker Method and other exercise books. I think they offer Yakov Neishtadt's classic tactics work - I remember some of the NEST+m kids becoming extremely dangerous tacticians after we studied this book together earlier in my career!
Of course, the best tactics problems will be the ones the student consistently solves! Good luck, and remember that some high quality work every day goes a long way.