Many of my students confuse the short e and short i sounds in words. This can be due to accent or vowel confusion, but it often comes out in both reading and spelling, and causes a lot of confusion. One way that we work on this is by using a speech-therapy technique known as “minimal pairs”. In this activity, the student is presented with a list of words that only differ in the vowel sound, such as “bed/bid” (they can be real or non-sense words). I provide a sheet of paper with the words printed out (usually on pastel paper, to reduce any glare for reading), and read one word from each pair at random. I have the student circle which one they heard, and we compare to see how many they got correct. Then, we switch, and they are the reader, while I see if I can get their words correct. This helps them to both be aware of how the vowel sounds and how it is produced. Many of my students improve greatly with this simple exercise!
Here is a free list of e/i words to use with your own students: short-e and short-i minimal pairs.