This is what I wrote. Not edited at all.
Loitering in the doorway of a busy coffee shop, he tried to blend in as he looked around. Jack hoped to spot Sarah soon. He also hoped she didn't spot him. If Sarah saw him this would all be over before it even started. Suddenly he saw her. She'd changed her hair in an attempt not to be recognised and was walking quickly with her head down. But there was no denying that it was Sarah.
A minute or two later Jack slipped from his hiding place and started just as quickly down that busy street after her. He kept a close eye on her but also kept looking around, so as not to be obvious. In reality it didn't work. It just made being caught more likely. Jack had never followed anyone before and was going by what they did in Spy Movies. Life isn't like Spy Movies however and it was only sheer luck that Sarah didn't look back and realise that after six months of hiding, her brother had found her.
I got good feedback when I read this out but I'd welcome any more feedback you'd like to leave here as you can never have to much. Constructive criticism is just as welcome too. I was surprised to realise that instead of being the scene I'd meant to take further but ran out of time for what I'd actually written was complete story in itself.
I will probably post some more writing prompts here as the class continues. And I intend to try and use the free writing technique most days if I can.