Readers 21-30 continue to build step-by-step on the information learned in Readers 1-20. Every Reader is only slightly more advanced than the one before it, meaning your student will be able to cope with the new material. In this way, progress is smooth, steady and free of anxiety.
Reader 21 teaches the new sound ch. As usual, we use it many times throughout the story to make it more memorable: e.g. chop, chin and lunch.
Notice how the Readers gradually grow in complexity. By this stage, children are already starting to read with confidence.