Use any fact fluency assessment you already have. Have students spin a spinner on their desk while they complete it. Every time they need to spin it, they make a tally or "x" at the top of the paper. Have them grade with an answer key or you grade it for them. They can record with a bar graph how many times they needed to spin as well as their percent with a point to make a line graph.
The bar graph will show speed and will hopefully go down through the weeks and the line will show accuracy, which will hopefully go up through the weeks.
This is a great alternative to your student who are afraid of the timer or timed test and very engaging!