A simple chart to draw observations and compare them. Some topics, like observing shadows, could be recorded a couple of times in the day. Others, like observing plant growth, may need to be recorded daily or weekly to compare.
My students have learned so much through the inquiry process, and I really look forward to seeing how they apply this way of thinking to other subjects in class. The inquiry process encourages students to ask questions and find the answers to these questions on their own. It builds important skills at an early age, and also opens their interests to the natural world and its properties.