*39%*:**Determining and Interpreting Resistive Electric Circuit Concepts Test (DIRECT)***39%*:**Potential difference and current in simple electric circuits: A study of studentâ€™s concepts***37%*:**PhET Teacher Ideas and Activities: Properties of Electric Circuits Using Only Circuit Construction Kit (CCK)***36%*:**Using Multimedia to Teach College Students the Concepts of Electricity and Magnetism***34%*:**Learning Motion Concepts Using Real-time Microcomputer-based Laboratory Tools***32%*:**Voltage Presented as a Primary Concept in an Introductory Teaching Sequence on DC Circuits***31%*:**Students' understanding of direct current resistive electrical circuits***31%*:**A Comparison of Inquiry and Worked Example Web-Based Instruction Using Physlets***30%*:**Voltage is the Most Difficult Subject for Students in Physics by Inquiry's Electric Circuits Module***30%*:**Cirque du Circuit: A Unit on Electric Circuits for High School Physics***29%*:**Using Multimedia to Teach Optics to College Students***29%*:**Concord Consortium: Electric Current***28%*:**Concept substitution: A teaching strategy for helping students disentangle related physics concepts***28%*:**Comparison of student performance using web and paper-based homework in college-level physics***28%*:**Connecting Concepts About Current to Quantitative Circuit Problems***27%*:**Difficulties in learning the concept of electric field***27%*:**Student's understanding of voltage in simple parallel electric circuits***27%*:**Students' understanding of voltage in simple series electric circuits***27%*:**Using the Lunar Phases Concept Inventory to Investigate College students' Pre-instructional Mental Models of Lunar Phases**