Sound/Spelling Cards are a small but really important component of teaching reading! 
They are a great visual to show exactly what you are teaching that week. If you have space in your house where you can put them up, at least for the week you are working on it, please do so! Put it in a place where your child can see it often so it stays fresh in their memory.
The card example above comes in the almost every pack of the Early Elementary Box.
It is a great opportunity to teach your children how to use reference tools. Sound spelling cards are reference materials in case they forget a sound, or need help spelling a word. This gives them the opportunity to look at the card and identify what spelling they are going to use, or decode a word they are stuck on. In my classroom we would have the cards up all year and would pull the particular sound card down and hang in on the whiteboard for easy reference when we were learning that sound/spelling pattern. I loved seeing my students look at the card when we did a writing activity or took a spelling test. It proved to me how valuable these reference cards were.
Here is a free printable that you can use when teaching the letters. Even just to put up somewhere in your home so kiddos can see it and start remembering that letters have sounds.
I also have the sound/spelling cards available for purchase as a packet below!
Reading Noodle 