I've used WTW for the past 3 years and I find it very beneficial but I test the students at the end of the week on the sounds they have practiced. My question to you is, why would you have them practice the word sounds but not test them on the sounds they've practiced? I use WTW just like I do my guided reading or strategy groups. Each group slowly moves through their word lists at their own pace (as a group). The first year I did the program I didn't test them but I felt I didn't know if they were really grasping the sounds, I send home the words with the students on Mondays, if they want to practice at home they are welcome to but we do enough work with the words at school, the kids do not need to. The list going home is more for the parents than for the kids.
I rotate through the list, for example I will have the 4 spelling lists (10 words only and they are random words from the 21 words their given to sort with). The groups are color coded white (A), blue (B), green (C) and yellow (D). I train the kids at the beginning of the year to be patient and wait while I do the test. It goes like this, group A number 1 is ...., group B number 1 is ...., group C number 1 is ...., group D number 1 is..., group A number 2 is ... etc. It takes about 20 minutes. I go slow enough that they hear the word but the others don't get too bored. I collect each groups word list all at the same time and then mark.
I only have two computers so I can't have the students taking tests on them. Another teacher in our school decided to take some of her guided reading time at the end of the week and test each group. I don't like taking time away from guided reading so I do my test in the 20 minutes just before lunch. That way I can mark the tests and hand them back to the students.
Hope this helps.
April Brown