This 10-minute video lesson discusses the differences between BC, BCE, AD and CE. It includes a little bit about the birth of Jesus as well. [Cosmology and Astronomy playlist: Lesson 65 of 85]

This 2-minute video lesson looks at the causes precession and other orbital changes. [Cosmology and Astronomy playlist: Lesson 74 of 85]

This 13-minute video lesson looks at the process of stars becoming white and black dwarfs. [Cosmology and Astronomy playlist: Lesson 18 of 85]

This 7-minute video lesson explains why cepheids pulsate. [Cosmology and Astronomy playlist: Lesson 32 of 85]

This 8-minute video lesson looks at why gravity gets so strong near dense objects. [Cosmology and Astronomy playlist: Lesson 33 of 85]

This 4-minute video lesson explains why S-Waves only travel in solids. [Cosmology and Astronomy playlist: Lesson 52 of 85]

This lesson for English Language Learners (ELLs) introduces the trend of dressing up as comic book or anime characters, cosplay. In this lesson, learners will practice reading, listening, speaking and writing. All activities are automatically graded with feedback provided to the learner upon submission.

Students learn about the many types of expenses associated with building a bridge. Working like engineers, they estimate the cost for materials for a bridge member of varying sizes. After making calculations, they graph their results to compare how costs change depending on the use of different materials (steel vs. concrete). They conclude by creating a proposal for a city bridge design based on their findings.

Students design a simple behavioral survey, and learn basic protocol for primary research, survey design and report writing. Note: The literacy activities for the Mechanics unit are based on physical themes that have broad application to our experience in the world — concepts of rhythm, balance, spin, gravity, levity, inertia, momentum, friction, stress and tension.

From the document:
"The Countdown Passages are strictly controlled stories that align with the phonics skills and Heart Words taught in Countdown. Aside from the
Heart Words in the passages, all of the words included are decodable according to the Countdown Scope & Sequence; however, due to the use
of some Heart Words that have not been explicitly taught in Countdown according to the guidelines described below, we consider the passages
to be “strictly controlled” rather than completely “decodable."

There are 12 fiction passages: one for each unit in Countdown, beginning with Unit 17. The passages provide students with longer, connected-text
opportunities to apply the skills they are learning in Countdown. In the Countdown workbook, students practice reading words, phrases, and
sentences. With the Countdown Passages, students extend their practice to longer sections of text. As students develop mastery and automaticity
with the skills taught in Countdown, the Countdown Passages can be used to reinforce these skills, to provide opportunities for practice, and,
ideally, to build fluency. Students will also gain confidence as readers. Reading text controlled for the specific skills students have already
learned allows them to read with success, leading to confidence and the willingness to tackle more difficult text in the future."

The students discover the basics of heat transfer in this activity by constructing a constant pressure calorimeter to determine the heat of solution of potassium chloride in water. They first predict the amount of heat consumed by the reaction using analytical techniques. Then they calculate the specific heat of water using tabulated data, and use this information to predict the temperature change. Next, the students will design and build a calorimeter and then determine its specific heat. After determining the predicted heat lost to the device, students will test the heat of solution. The heat given off by the reaction can be calculated from the change in temperature of the water using an equation of heat transfer. They will compare this with the value they predicted with their calculations, and then finish by discussing the error and its sources, and identifying how to improve their design to minimize these errors.

Welcome to the UnboundEd Mathematics Guide series! These guides are designed to explain what new, high standards for mathematics say about what students should learn in each grade, and what they mean for curriculum and instruction. This guide, the first for Kindergarten, includes three parts. The first part gives a “tour” of the standards for Counting & Cardinality using freely available online resources that you can use or adapt for your class. The second part shows how Counting & Cardinality relate to classification of objects in Kindergarten (K.MD.B). And the third part explains where Counting & Cardinality is situated in the progression of learning in Grades K-2. Throughout all of our guides, we include a large number of sample math problems. We strongly suggest tackling these problems yourself to help best understand the methods and strategies we’re covering, and the potential challenges your students might face.

This is a collection of sample counting circles you can use in your classroom as part of number talks.

Students practice counting sequences by standing in a circle and counting one by one.

Counting Collections is an important mathematical routine that students or families can do with very little guidance at home. Teachers could make kits with available resources for use at home, or send suggestions for commonly found objects that families could use for counting practice at home.

Counting Collections are just as described; they are collections of items that students count. Depending on your students, you will need several different kits. Kits hold several different collections of items.

This short video and interactive assessment activity is designed to teach second graders about counting cubes and creating a place value diagram.