In 1792, recent college graduate Eli Whitney moved to Georgia to work as a tutor on a plantation. There, Whitney learned that southern planters were eager to make cotton a profitable crop. Once cotton was picked from the field, seeds had to be removed from the cotton fiber by hand before cotton could be sold. This process was labor-intensive and time-consuming, and it limited the amount of cotton that planters, relying on the work of enslaved people, could produce.

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.

Visualize the electrostatic force that two charges exert on each other. Observe how changing the sign and magnitude of the charges and the distance between them affects the electrostatic force.

As humans, we thrive on social connections and group associations. But this tendency can also lead us to be suspicious of people outside our group. This fear -- xenophobia -- can be overcome by more exposure to people who are different from us. However, the internet can often make this more difficult. Help students recognize this challenge and find strategies for navigating content online.

Students explore the science of microbial fuel cells (MFCs) by using a molecular modeling set to model the processes of photosynthesis and cellular respiration—building on the concept of MFCs that they learned in the associated lesson, “Photosynthesis and Cellular Respiration at the Atomic Level.” Students demonstrate the law of conservation of matter by counting atoms in the molecular modeling set. They also re-engineer a new molecular model from which to further gain an understanding of these concepts.

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.

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

Students who work on this task will benefit in seeing that given a quantity, there is often more than one way to represent it, which is a precursor to understanding the concept of equivalent expressions.

This task gives students another way to practice counting and gain fluency with connecting a written number with the act of counting. This task should be introduced by the teacher and would then be a good independent center.

The most engaging way to practice counting with students is to have them count meaningful things in their lives. Since five-year-olds are very focused on themselves this is easily done by allowing them to count themselves, their friends and objects within the classroom that relate to their daily lives.

This challenging problem and brainteaser gives first graders an opportunity to compose and decompose squares.

This is an instructional task related to deepening place-value concepts. The important piece of knowledge upon which students need to draw is that 10 tens is 1 hundred.

Using solar images and date obtained from Astronomical Observatory of the University of Coimbra lets you study the sunspots and their behaviour over days.

The objective of this lesson is to gain automaticity counting to 100 and to establish the importance of multiples of ten. The final goal of this lesson is for students to be able to count by tens and articulate the term for this.

In this activity, students use a range of primary and secondary sources about San Francisco's Chinatown (1880s-1920) to explore what the community meant to residents and to outsiders.

This task involves solving equations with rational coefficients, and requires students to use the distributive law ("combine like terms"). The equation also provides opportunities for students to observe structure in the equation to find a quicker solution, as in the second solution presented.

This art history video discussion examines Gustave Courbet's "The Artist's Studio; A real allegory summing up seven years of my artistic and moral life", oil on canvas, 1854-55 (Musee d'Orsay, Paris).

Focusing on the means used by the Incas to send messages over long distances, the lesson introduces students to the Inca Empire, which extended from northern Ecuador to central Chile and from the Andes to the west coast of South America between 1200 and 1535 CE.