One digital tool I've stuck with for assessment and have used a lot of this year in Pre-Kindergarten, is the recordable whiteboard. There are a lot of different options for recordable whiteboard apps now and it takes time to sort out which is best for certain uses and functions. My two favourites are Explain Everything and Educreations and they have become indispensable resources for formative and summative assessment.
For me, they document what pen and paper cannot: live work and thinking. Capturing children's activities in this way allows me to revisit the moment and interpret and re-interpret what I observe, rather than relying on a note I have jotted down, which can be influenced by my interpretation and judgment in the moment.
I use this app to document conferences with students, especially for summative assessments in maths and units of inquiry. With the age of students I teach, this is more of a teacher tool as there are a lot of different functions and small buttons. You can quickly take or import photos, annotate and voice record. I find that all of these features together often enhances students' performance on interview-type assessments. The voice recording of the assessment also preserves my own contribution, helping me to remember which questions (on top of the key assessment questions) I have asked and how I have influenced the direction of the conversation, including the students' answers. The app easily exports files as videos to Camera Roll & YouTube.
I use this app when I want my students to be able to document their own formative assessments independently during their free time or at stations. There are fewer and bigger buttons which means that it is easier to navigate and use independently for young learners. I often use Educreations to assess students' letter and number formation, so I have living documentation of what the student is doing, rather than just my anecdotal notes.
(Note: I have posted a screenshot of the video captured below because you cannot embed Educreations recordings.)