Stephen Hughes wrote:ἐρχόμενον jumps between masculine accusative singular and neuter nominative singular in those simplified sentences.
The ὃ makes a major break in this sentence.
To me, that depends on how you interpret this sentence. Regardless, in these sentences τὸ φῶς ἦν ἐρχόμενον:
- ἦλθεν τὸ φῶς
- ἦν ἐρχόμενον τὸ φῶς
- ἦν τὸ φῶς ἐρχόμενον εἰς τὸν κόσμον
- ἦν τὸ φῶς τὸ ἀληθινὸν ἐρχόμενον εἰς τὸν κόσμον
That leaves the one that comes directly from the text:
- ἦν τὸ φῶς τὸ ἀληθινὸν ὃ φωτίζει πάντα ἄνθρωπον ἐρχόμενον εἰς τὸν κόσμον
If it's periphrastic, then it still says τὸ φῶς ἦν ἐρχόμενον, "the light which was coming" (neuter nominative singular). If not, then it might be saying τὸ φῶς φωτίζει πάντα ἄνθρωπον ἐρχόμενον εἰς τὸν κόσμον, "the light enlightens every person who comes into the world" (masculine accusative singular). There are other possible interpretations. Regardless, the scaffolding should probably build to one particular interpretation, rather than bring in all of this complexity at this basic level of instruction.
Here's the Expositor's Greek Testament:
ἐρχόμενον has been variously construed, with ἄνθρωπον, with τὸ φῶς, or with ἦν.
(1) The first construction is favoured by Chrysostom, Euthymius, the Vulgate, and A. V[25], “that was the true light which lighteth every man that cometh into the world”; or with Meyer, “the true light which lightens every man coming into the world was present” (ἦν = aderat). To the objection that ἐρχόμ.… κόσμον is thus redundant, Meyer replies that there is such a thing as a solemn redundance, and that we have here an “epic fulness of words”. But the “epic fulness” is here out of place, emphasising πάντα ἄνθρωπον. Besides, in this Gospel, “coming into the world” is not used of human birth, but of appearance in one’s place among men. And still further ἐρχόμενον of this verse is obviously in contrast with the ἐν τῷ κόσμῳ ἦν of the next, and the subject of both clauses must be the same.
(2) The second construction, with τὸ φῶς, was advocated by Grotius (“valde mihi se probat expositio quae apud Cyrillum et Augustinum exstat, ut hoc ἐρχόμενον referatur ad τὸ φῶς,” cf. John 3:19, John 12:46, John 18:37), and has been adopted by Godet, who renders thus: “(That light) was the true light which lighteth every man, by coming (itself) into the world”. If this were John’s meaning, it is difficult to see why he did not insert οὗτος as in the second verse or τοῦτο.
(3) The third construction, with ἦν, has much to recommend it, and has been adopted by Westcott, Holtzmann, and others. The R. V[26] margin renders as if ἧν ἐρχόμενον were the periphrastic imperfect commonly used in N. T., “the true light which enlighteneth every man was coming into the world,” i.e., at the time when the Baptist was witnessing, the true light was dawning on the world. Westcott, however, thinks it best to take it “more literally and yet more generally as describing a coming which was progressive, slowly accomplished, combined with a permanent being, so that both the verb (was) and the participle (coming) have their full force and do not form a periphrasis for an imperfect”. And he translates: “There was the light, the true light which lighteth every man; that light was, and yet more, that light was coming into the world”.
Here's ICC:
ἦν τὸ φῶς κτλ. The constr. of the sentence has been taken in different ways, and the ambiguity was noticed as far back as the time of Origen.2
(I) The Latin, Syriac, and Coptic versions take ἐρχόμενον with ἄνθρωπον. The Light enlightens every man who comes into the world. But if this were the meaning, (a) we should expect παντὰ τὸν ἐρχόμενον rather than παντὰ ἄνθρωπον ἐρχόμενον; (b) these words are wholly redundant, for they do not add anything to “every man”; (c) the expression “coming into the world” is not used elsewhere by Joh_3 of a man being born (16:21 is no exception). This last consideration excludes also the rendering “every man, as he comes into the world,” apart from the fact that, although Wordsworth suggests it in his Ode, the idea of any special Divine enlightenment of infants is not Scriptural.
(2) It is better to take ἐρχόμενον with φῶς (so R.V.). Jn. several times uses the phrase “coming into the world” of the Advent of Christ (6:14, 11:27, 16:28, 18:37); and elsewhere (3:19, 12:46) in the Gospel Christ is spoken of as “light coming into the world.” And if we render “the Light, which lighteth every man, was coming into the world,” the constr. of ἦν with the present participle as used for the imperfect is one which appears frequently in Jn. (see on 1:28 below). ἦν … ἐρχόμενον means “was in the act of coming.”
Westcott, while retaining this meaning, endeavours to combine with it the conception of the Light having a permanent existence (ἦν, the verb used in v. 1). “There was the Light, the true Light which lighteth every man; that Light was, and yet more, that Light was coming into the world.” This seems, however, to attempt to get too much out of the words, and on our view of the whole passage the meaning is simpler.
We are still occupied with Jn.’s comment (vv. 6-9) on what the Logos Hymn has said about the Light (vv. 4, 5). The Baptist was not the perfect Light, but he came to bear witness to it; and this perfect Light was then coming into the world. When Jn. wrote the First Epistle he could say, “The true Light already shineth” (1 John 2:8), but it was only coming at the time when the Baptist’s mission began. Jesus had come into the world, indeed; but He had not yet manifested Himself as the Light.
For a beginning class, I think it's best to pick one interpretation and leave this complexity until later. The scaffolding you choose depends on the interpretation you pick.