“…The ability to enumerate unit-cubes in 3D arrays is crucial for understanding volume and the volume formula (Battista & Clements, 1996;Smith & Barrett, 2017). However, enumerating unit-cubes in a 3D array has shown not to be an easy task for many students (Battista, 1999;Battista & Clements, 1996;Ben-Haim et al, 1985;Finesilver, 2015Finesilver, , 2017Vasilyeva et al, 2013). The students need to interpret the array as a space-filling object, including units inside the array (Finesilver, 2015).…”