I have been using this FREE app for several years now Ideal as part of assessment, and can be used regualry as each App is activated it generates new challenges …
The full price app is £9.99, however you can try the 'lite' version for free
SERC / Newbridge School
Barley Lane Campus, 258 Barley Lane
Goodmayes
Ilford, IG3 8XS
SERC is a service and information centre brought to you by Redbridge.