Unlike the flowcharts of my youth which had to be drawn by hand, tested with discipline and were impossible to change, pupils can not only create flowcharts digitally but can actually run them to make testing and debugging far easier.
Rather like block programming, flowcharts that run (yes, I know that makes them programs!) allow pupils to build up solutions to problems without worrying about too much syntax. They are another way of embedding the computational thinking skills needed for programming later. The flowcharts can be used in following programming units to complete the circle.
Don't forget about testing, even test-driven development with flowcharts, to make sure pupils are checking their work.
Flowol is a really useful tool here because the mimics (images of the problem but with lights turning on etc.) mean you almost have physical computing without the batteries. The fact that the flowcharts run and you can step through, pause etc. means you have really written a program but without any worries about syntax.
I often ask pupils to annotate flowcharts - either theirs or mine to explain how something works. This can be tricky to get going, pupils often just write what is written on the block, which is pointless! It is important to break complex tasks down; pupils should get used to developing solutions incrementally - testing as they go.
The mimics in Flowol are really useful and I think this tool is worth the cost (a one-off fee of around £300+VAT for a site licence which includes home installation for homework)
This unit starts out with a computational thinking task and then reviews the concepts of sequence, selection and iteration. Pupils are given tasks to solve using Raptor with some scaffolding to start with.
We use OneNote for some notes in Year 9 so pupils upload screenshots of their flowcharts along with a test table. This is a good point to reinforce the need for testing and I ask pupils what test data should be used to fully test a solution. Attention to boundary values is important, of course.