To enable this function on the iPad, go to your Settings. Under the 'General' option, choose Accessibility. At the bottom of the first box, select "Speech" and enable the top option "Speak Selection".
My learners used this function within Explain Everything. They simply highlight the piece of text they are unsure of and select "speak". The text will be read to them and they know exactly what my instructions said. NB: In Explain Everything, the text cannot be locked down if you are wanting to use the speak function - I do occasionally forget this but my learners know to just unlock the text to use this function.