I have always taken an EYFS approach to my science observations. What I mean by this is that I try to capture children's scientific working and thinking in the moment. It is important you plan in time to observe children and have discussions about their ideas and reasoning within science lessons. I capture these on my science observation records (attached below), however a post-it will also do the same job.
I am a big believer that it is important not to reinvent the wheel - working in schools who has the time? Therefore, I would recommend using the TAPs Primary Science assessment materials.
Moderation templates based on a school using the TAPs assessments as part of their overall science assessment. I highlight what has been achieved and what assessment units have been taught. I also tick what types of enquiry are evident. I then annotate with additional notes/ information. It can be beneficial to blow these up to A3 to allow more space for annotation.
Other Assessment Documents