The 1.75 to 2.5 inch Small Fries, Crappie sized carrots, the Flap jack, or Stinger Wutz-It would do nicely.
If he likes bream fishing as well I would lean toward the Small Fries. If he likes to do a little spec and /or bass fishing as well as crappie fishing I would lean toward the Stinger Wutz-It, larger Flap Jack, or larger crappie carrots. All are excellent baits in my opinion.