If you have been tasked with designing a website that is child friendly then you need to think carefully about the layout of it as well as the safety aspect. Depending on the age of the children that the site is aimed at and the content on the site, you may need to build an age verification or parental login area.
If you are designing a site that is aimed at 5-8 year olds then you should make it very graphical, with bright colours and lots of interesting areas for them to browse. If it is an educational site then you need to ensure that the information is easy to find and displayed in a way that is going to appeal to their age. It may be that you make it interactive so that they can press buttons or submit answers through the website. Adding videos and moving graphics can also help to keep them engaged.
Safety is of the upmost importance when it comes to online activity. If there is anyway of people communicating with each other, this need to be programmed in such a way that parents are able to monitor this and put restriction on who their child can communicate with.