This depends on a number of factors and therefore should be discussed specifically with your course coordinator. It depends on
(a) the course you are taking medicine, nursing, pharmacy etc
(b) the year of study you are in 1st year, 2nd year and so on
(c) the level of qualification you are pursuing e.g. degree, masters, PhD etc... You will have to satisfy your course coordinator, laboratory demonstrator, or placement facilitator with the evidence you supply, but it is also essential that you are happy with the evidence that yourself. Have you demonstrated that you completed or attained a certain level of competency in a task to your own satisfaction? Being able to evaluate your own performance and identify your own continuing professional development is an essential component of your development as a healthcare professional.