I relaxed my hair, but as soon as I shampooed it, the curliness came right back. What happened?

The relaxing process may have been stopped too soon. When that happens, it can look like the hair is completely relaxed, but when it is rinsed and shampooed, the natural curl is still there. The process must be correctly timed. Look for instructions that might indicate how long you should wait to shampoo. This could be a contributing factor.