Illustrative Mathematics
Illustrative Mathematics: G Mg How Many Leaves on a Tree? (Version 2)
In this task, learners must estimate the number of leaves on a large tree, taking into account various complex factors such as the area shaded by the tree, the area of irregularly shaped leaves, the uneven distribution of leaves, the...
Science Education Resource Center at Carleton College
Serc: Air Is Matter
It's difficult at times for younger young scholars to realize that air has mass. Matter is something that has volume (takes up space) and has mass (*can be weighed). Air does take up space, even if we can't see it, and air has weight,...