Wordshark and Numbershark are able to be tailored completely to your child's level. They provide very short, focussed tasks in the form of games and give a reward game for each completed task. If used properly, they can be very valuable and can help children's number/word work. However, not used properly, the children gain very little benefit from them.
At school we used to use Numbershark more than Wordshark. I used it with my lower Y3 maths set, and it was very good for practice of the basic stuff - number bonds to 10, 20 or 100, tables, etc. We never really got past these! However, I was very clear with the group which games I wanted them to play as there were some which didn't practise the number work. Very quickly they learned which ones to play though.
So, I would say, used properly, it's worth the money, and to use it properly involves:
- looking at it in advance to decide where the child needs to start.
- talking the child through the games you want them to use and how they work.
- showing them how to work out the answers to the type of questions they will meet.
- watching them as they work to see how they are working out the answers and how quickly they can answer them.
- intervening if necessary to help them become more efficient/accurate.
- moving them onto more difficult work when needed.
Obviously sometimes they can be allowed to 'play', but too often (and I have seen this in my old school) it is used by teachers as an easy lesson, which is why the children do not make progress.
Gosh, that was a long post! Sorry and well done if you reached the end!