Operations between fractions
The sum of two fractions
The following applet, created by Anthony OR 柯志明 (inspired by John Ulbright's applet "Adding Fractions - Visual" (https://ggbm.at/szwBQ7wa)), illustrates how to find the sum of two fractions.
The product and the quotient of two fractions
The following applets can be found are by Profs de math de la CSMV