Have your child use the letters to form the sight words you are practicing today. If necessary, get the letters already in to the words. Your child will choose a word, pick the first letter and stamp it, then the child wipes the letter off on the sponge and returns it to the tray.
You may need to sit with your child during this practice. Remember to say the word over and over and over! The more opportunities to hear it, the faster she will learn it!