The Purpose of the Mental Computation folder cards

The folder cards are used to show the visual aspect of what is being taught with mulitplication or division. With multiplication it is actually the same number being added until you arrive at the result. For example, with 3x4 it iactually 3+3+3+3. another way to explain multiplycation is by grouping into sets.

The ACARA is for year 2. The strand is Number and algebra, substrand is Number and Placement Value. Recognise and represent multiplication as
repeated addition, groups and arrays (ACMNA031) the elaboration for this section is

representing array problems with available materials and explaining reasoning
visualising a group of objects as a unit and using this to calculate the number of objects in several identical groups.

These cards can then be used for division as well. the concept is found in ACARA in year 2, strand Number and Algebra, substrand is Number and Placement Value. Recognise and represent division as grouping into equal sets and solve simple problems using these representations
(ACMNA032)

the elaboration is

dividing the class or a collection of objects into equal-sized groups
identifying the difference between dividing a set of objects into three equal groups and dividing the same set of objects into groups of three