ABC Ya! has a wide range of games for children aged 4 to 11 years. It has both language and maths games divided by year level. These games are enjoyable and are popular with students.
*The games have to be played on a desktop or laptop for it to work in the free version.
It is a free website and there is also a paid subscription that gives access to playing all games on mobile devices and is add free.
Spelling City is a website that allows your children to play spelling games based on a pre-made spelling list or a list of their choosing (for example their class spelling list). There is a membership fee (about 35$ a year) that gives access to a wide range of spelling and vocabulary games and activities but there is also a small number of games for free that can give you a sample of what this site provides.
Education.com has a wide range of spelling games (as well as games in other areas) that your children can play for free. The website does require you to create an account in order to access the free games. You will be prompted to do so after trying a couple of the games.
Home Spelling Words has a series of free spelling games that can be played using different grade level word lists or with your own inputted word list.