Bishop Crowther worked with a team of literate Igbo missionaries/translators (including J. C. Taylor, who went on to finish his own Igbo translation of the New Testament) to produce the first Igbo primer. And they used an orthography that has since become obsolete.

If this is what you are understand as 'crowther taught the ibos the current ibo alphabets which they now use in spelling their names', then I fear you may be incapable of passing a verbal reasoning test.