Montessori cultural education includes both art and science. It is a good idea to express what you have learned in science through drawing.
The easiest science subjects to use are probably plants and animals which are familiar. Plants, in particular, are easy to find in parks and roadsides. Dandelions can be recommended because it is very familiar and its appearance changes with the seasons. When studying nature in Montessori, it is recommended to learn and fully observe the various forms of plants and animals as they change with the seasons.
Trees are also recommended. You can learn about seasonal changes by comparing deciduous trees such as maple and oak, and evergreen trees such as pine and fir. It will be easier to understand if the child observe deciduous trees and evergreen trees in fall and winter.
This picture shows the seasonal changes of dandelions in one. I tried to capture three different appearances of a dandelion.