The main premise of working with children outside is to reconnect them with nature and limit the screen-time they get, but it's impossible to get away from the great apps/features of an iPad that lend themselves to when you step outside the classroom.
iMovie (Free with eligible hardware)
Lots of application for recording/editing videos taken during outdoor explorations. Perhaps most powerful when back in the classroom. Musical trailer to represent a PE Lesson or developing a full scale 30-60 second evaluation of the school's environmental practices.
Pic Collage (FREE)
Other apps are available, like Moldiv, but I think PicCollage gives simple templates to collect and share photos from the children's adventures in turning over stones/logs and sharing the images taken during the woodland walk or school visit.
Use this to create short picture montages after performances and educational visits. Children can quickly create videos for sharing on social media or the school website.
PhotoBooth (Built In)
I'm a fan of all the image distortions on this app. I've let the children in EYS/KS1 go on a walk watching through the 'Thermal' view. "It's really like another world!" John (5)
Taking photographs through the filter, can then lead to some wonderful Warhol-esque artwork.
Record thoughts, observations, vocabulary, actions for use in writing later. Record shapes in the environment, using text or sound for younger or SEND children.
I-Beam Mag. Glass (FREE)
Great free app with infinite zoom. Fantastic for up-close photographs of leaves, bark, soil samples and mini-beasts.
Tim O's Compass (FREE)
Send the children on a treasure hunt like real pirates following the map. Develop awareness of direction.
Clock (Built In)
Use the clock, stopwatch or timer. I set it running as the children go out and then they know precisely when they should be back!
Calculator (Built In)
Work out maths problems while out and about!
Designed by a Science Leader Steven Lewis-Neill, the app has 100s of web based activities and tasks for KS1/2 Sc2 Topics - easy login for children and will track their progress (Needs a subscription).
Warblr (iPhone app) £3.99
Great app at a reasonable price - the microphone identifies bird songs and brings up a fact-file on the bird it picks up. Makes for a great survey of wildlife, outside of insects/bugs!
Birds of Britain Pro (Lite Version FREE / Pro Version £2.29)
Similar to Warblr, but fact-files on birds and sound files of songs. Free version has 30 birds, Pro version has 199 birds. I like the quality of the information texts on the go.
BBC Weather (FREE)
Using the app to develop the children's awareness of symbols and make predictions of the weather over time, can be used in conjunction with cloud identification apps (Cloud Types £0.79 or Coton £1.49).