This optional sequence of three lessons can be done any time after the first unit in the course. The activities across the three lessons build on one another and should be done in order. It is not necessary to do all three lessons to get some benefit, although more connections are made the further one gets.
As students progress through the activities, they see a variety of ways some shapes can be put together to build a tessellation and that not all shapes can tessellate the plane. They start with general tessellations, and then look at regular tessellations. Finally, they generalize which polygons can always make a tessellation. 

All standards in this unit have been addressed in prior units. This section provides an optional opportunity for students to go more deeply and make connections between domains.

This optional sequence of three lessons can be done any time after Unit 6 in this course. The activities in these lessons provide students a chance to go more deeply and apply grade 8 mathematics to a real-world context. Students get a chance to engage in aspects of mathematical modeling throughout this section. The activities in these lessons build on each other, and should be done in order. It is not necessary to do all three lessons to get some benefit, although more connections are made the further one gets.

In this section, the lessons and activities follow the steps of the modeling cycle and result in students creating a simple mathematical model to predict temperature. Throughout this section, students make and discuss choices, assumptions, and approximations as part of their work.

As an extension, students can make more decisions themselves. Groups could create different proposals of how to investigate the relationship between temperature and latitude, present, get feedback, finalize, and continue with different data for their model. Students could also investigate if there is a similar association between latitude and temperature in other parts of the world. For the full modeling cycle, they could then revise their assumptions and come up with a revised model.

All related standards in this unit have been addressed in prior units. This section provides an optional opportunity for students to go more deeply and make connections between domains.