These are all tools with complexity "easy"!
Team timer (also: Team development timer)
The team timer is a stage model of team development. The typical group process comprises 5 stages: forming (forming stage), storming (conflict stage), norming (stage of developing rules and norms), performing (working stage) and adjourning (resolution stage).
Tree diagram
A tree diagram is a method to create a structured and interrelated overview of a topic or problem on different levels. Therefore, it is possible to depict complex correlations in a comprehensive way and to reveal interactions.
User Personas
User Personas are a method that enables to analyze the relevant and unfulfilled applications of a product or service with regards to the needs of customers.