The obvious place to start with EY and KS1 is Scratch Jr. it’s a free iPad app (works on other devices too) and it’s lovely. There are many classroom resources available for it.
KS2, please be aware that this isn’t Scratch though, it’s a cut down version of it, and there really isn’t enough meat in it to be of use much beyond Y2. The number one choice for coding at KS2 is Scratch itself, and with good reason (though other options exist). Until reasonably recently Scratch was not available for iPads. Now it is (Scratch 3).
To make it work properly you will need to create a teacher accountand then create online logins for your children to use; this is the only way they will be able to save their work.
There are still one or two limitations you’ll need to consider. At present it’s not possible to include key presses in your coding (unless you are lucky enough to have keyboards with your iPads) and any kind of mouse / pointer following behaviour won’t work either, for obvious reasons!
A surprisingly large number of education resources use these. The latest incarnation of the Herefordshire Computing Progression (2020) includes many projects, allocated to year groups that will work though.
Alternatives to Scratch on iPads include Pyonkee. The interface looks identical to old Scratch 1.3. However, you will quickly realise that an application that works well with keyboard and mouse doesn’t necessarily translate well to a touch device.
Tickle is an excellent app. Very much based on Scratch and includes blocks that make use of the iPad’s accelerometer so that you can control sprites (or “actors” as they are called in Tickle) by tilting the iPad in different directions. Another feature of Tickle is that it will control any combination of many external devices such as Sphero, LEGO WeDO 2.0, Ollie and several Parrot drones.
Support for Parrot drones was removed from Tickle at the end of 2016 (not quite clear why) but you can regain it by opening a project that contains a drone “actor” Please contact me if you’d like these – I have saved them from an old version of the app.
Tynker is another excellent option. Rather like Tickle (above) but allows projects to be created at a more sophisticated level. Tynker also has a great deal of lesson support / schemes of work which comes at great cost but you don’t need it and the free version of the app is adequate. Tynker also supports an impressive range of robotic devises, including Parrot drones.
Here are some activities for group work with KS2 when programming Parrot minidrones: