I highly recommend an activity I printed out from the Teachers pay Teachers website. It is a free worksheet that you can print out from this link: http://www.teacherspayteachers.com/Product/FREE-Kindergarten-Word-Family-Independent-Work-at-word-family
This activity is designed to practice the -at word family with reading, spelling and writing words from common short vowel word families. We worked with recognition of the sound of the letters. The website suggested to do this activity in a week but we did it in one day, as it was short exercises and he was doing quite well and managing to complete all the exercises required. Great worksheet, I approve.
I couldn't make a copy to upload on my blog for you all to see it, but if you click on the link above you will be able to connect to the page.