Observing Latent Heat with a Portable Hand Warmer

In this lesson, students observe a teacher-directed demonstration that provides a conceptual understanding of latent heat, the "hidden heat" present in all changes from one phase to another, by using a hand warmer. Educational levels: High school, Middle school

Observing Latent Heat with a Portable Hand Warmer

This teacher-directed demonstration provides a conceptual understanding of latent heat. Using the example of a chemical hand warmer, students learn about phase changes from liquid to solid and from solid to liquid and observe that one of these phase changes releases heat while the other requires heat to be added. These concepts are then reinforced in a demonstration which involves heating water and ice water. Evaluation suggestions are also included. Educational levels: Middle school, High school

Observing Latent Heat with a Portable Hand Warmer

In this lesson plan students observe a teacher-directed demonstration that provides a conceptual understanding of latent heat. A reusable handwarmer that uses a solution of sodium acetate is used to illustrate phase changes and the release of energy and latent heat. Educational levels: High school, Middle school, Undergraduate lower division

Financial Constraints and Investment: Assessing the Impact of a World Bank Loan Program on Small and Medium-Sized Enterprises in Sri Lanka

The authors examine the investment behaviour of a sample of small, credit-constrained firms in Sri Lanka. Using a unique panel-data set, they analyze and compare the activities of two groups of small firms distinguished by their different access to financing; one group consists of firms with heavily subsidized loans from the World Bank, and the other consists of firms without such subsidies. The use of program-evaluation techniques reveals that the relaxation of financing constraints did not affect economic efficiency for the group of firms that received subsidized capital.