How can a mixed group of male and female students be taught at home, and should females be separated from males when a sister is present as a mahram?

It is permissible to teach both genders with Islamic controls, such as separation between them, female students wearing hijab (definition), and no private seclusion. However, it is not permissible to teach women who are displaying their adornments (mutabarrijat) due to the impossibility of lowering the gaze. It is obligatory to suffice with teaching males and veiled women. And fearing Allah brings sustenance, facilitates matters, expiates sins, and magnifies reward.