This constitution isomer of penatdiene is an allene and it contains "cumulated" double bonds. Notice that the pi-orbitals of the two double bonds are in planes that are perpendicular with regard to each other. Consequently, the methyl groups are not in the same plane; the Newman projection down the C=C=C skeleton shows the dihedral angle between the methyl groups to be almost 90 degrees. Finally, examine the conformations about the C-Me bonds. Are they eclipsed or staggered?