Hi assessment means the different ways you, your colleagues and external organisations check on children's learning and development.
Page 265 of the EYE handbook is good reading, it looks at how the observations you've listed are method of assessment because they gather information to enable practitioners to make a determinations or judgements about how a child's learning and development is going ie. they inform your practice by telling you what a child is doing well, what they find interesting, if there are any concerns.
Page 267 then looks at what checklists mean, simple note taking, free description, event sample and informal observations.
What observations do you do in the setting? Are they any good at telling you how a child is doing, would you be able to say how many other children/adults an individual child likes being around/ what activities and areas of the setting they find interesting eg. sand tray/jigsaws/ cars/ and they language that's being used?
The EYFS 2017 also looks at assessment and what your setting is expected to do
page 13+
Hope this helps a little more xx