There are many ways to divide and emulsify the lens nucleus in cataract surgery. Some advanced surgeons will chop the nucleus into many smaller segments before removing a single one from the capsular bag. Others find it easier to remove one nuclear half first before going after the second hemi-nucleus. This is the technique that can be easier to learn because once the first half is removed there is much more working room within the capsular bag.
click below to see the technique of chopping one half before the other: