We used Timez attack quite a bit this past year. DS was frustrated with it because he felt like he had to answer the drills too quickly. He does have a relative weakness with processing speed, so I guess that makes sense.
My DD9 came to me in tears tonight because she couldn't get off the current level without being able to answer drills in 2 seconds "and it's a really quick two seconds too mum!". I told her to play something else but she was both devestated and desperate go keep going,, poor thing. She wants to play and to progress but she's just not that quick...
When my DS could answer the fact quickly but couldn't type it quickly enough, I just typed the answer in as he called it out. Sure, it meant that I had to stand there the whole time he was playing, but it definitely removed the frustration factor. Sometimes, if I was busy, though, I'd have DS's older brother or sister type the answers in!
