In Session 5 of computing we spent some time using the program Scratch.
I think Scratch is a good tool to use in primary schools for Computing because it can be quite simple to use and is a good starting point to get children to start basic programming.
Scratch is very good because it includes all the basic instructions to get a Sprite to do something, so the basic programming tools and algorithms are already in place, the children need to understand which instruction needs to go in which order. There are simple worksheets as well that the children can follow, and then they can use their finishing product and improve it. I did the same, when I used the instructions I found that one of my sprites was not working the way i wanted it to, so I was able to change it.