Free Presentations in PowerPoint format. Fractions Powerpoints (several) Fractions. Rules for Fractions. Fractions (several) Fractions (several) 4th Grade Word Problems and Fractions. Decimals and Fractions. Adding and Subtracting Fractions. Multiplying Fractions and Mixed Numbers. Multiplying and Dividing Fractions. Dividing Fractions ... Jan 15, 2020 · Free, fun, interactive simulations for science and math instruction. A collection of fun, interactive, research-based simulations for science and math instruction in Grades K-12 and university, developed by PhET Interactive Simulations at University of Colorado Boulder (https://phet.colorado.edu).