The audio recordings were made using www.vocaroo.com, which allows you to upload sound files linked to QR codes. (See below)
As you can see above, you cannot use the audio recording function on ipad, so I used the good old TTS Easimic and uploaded the sound file.
Once uploaded/ recorded you are taken to a page on which you can listen to the clip and download a QR code. I pasted this onto the word document for the pupils to scan.
The pupils used Kaywa reader app to scan the codes, listen to the audio and them wrote the number.
Initially the pupils used the place value grid suggested by Michael Tidd (https://michaelt1979.wordpress.com/2015/07/25/stop-teaching-thousands/), but soon moved away.
The combination of QR codes and Vocaroo is definitely worth further exploring. Post your ideas below!