I'm a rule stickler, and would never advocate going out & buying thicker shoes, however, don't let him wear thin soled shoes (flip flops or sandals or even converse) have him wear his regular tennis shoes. They will be more comfortable to walk in as well as adding a little extra height & not look like you went out & bought shoes solely for "heightening" purposes. When my daughter was at this stage we went to the park & she dresses as Minnie Mouse, complete with red & white polka-dot MaryJanes. Needless to say, those MaryJanes were thin-soled & she didn't make the height requirement. The next day, we had her wear her tennis shoes, she made the height requirement then