As some of the commentors on your question rightfully said, the answer you seek is too broad and encompassing to be contained in a simple response. You need to read the following texts to obtain material you need to teach your students. Please note, some verses from sources I state below are only a SAMPLE or a sprinkling from the comprehensive material that exists in these texts:
I. Rig Veda
Rig Veda - Verse I.XXXV.IX
"The sun moves in its own orbit but holding earth and heavens [other heavenly bodies] in a manner that they do not collide with each other through the force of attraction."
Rig Veda - Verse X.XXII.XIV
"This Earth is devoid of hands and legs, yet it moves ahead. All the objects over the earth also moves it. It moves around the sun."
Rig Veda - Verse V.XL.V
"O Sun! When you are blocked by the one whom you gifted your own light [i.e. the moon], then earth will be surprised by the sudden darkness."
Approx. 13 years ago I visited the Museum of Natural History in New York City, USA. In this museum, there was a section/floor dedicated to Asian History and in that section they had a 12" X 12" plate on the wall of the South Asian section, and that wall plate had embossed on it the discovery of Aryabhatta of India circa 470 A.D. that earth was a globe and not a flat land and that he was the first to calculate the circumference of earth (which is spot on per modern calculations) and that he was the inventor of Trignometry (he created the sine function). I took a photo of that wall plate at that time but I do not know where it is stored in my computer/online drives now. However, here is a reference he gave in his work from that era, called Aryabhattiyam:
He gave the circumference of the earth as 4,967 yojanas and its diameter as 1 581 1/24 yojanas. Since 1 yojana = 5 miles this gives the circumference as 24 835 miles, which is an excellent approximation to the currently accepted value of 24 902 miles.
Around 570 A.D., Varaha Mihira in city of Ujjain in India wrote his treatise on Astronomy and astrology called the PanchasiddhAnta, which had 5 texts in it, namely the Surya siddhAnta [Doctrine of Solar System & Motions], Vasishtha siddhAnta [Doctrine of the Major/Minor Bear constellation], Pulasa siddhAnta [Doctrine of the Greek city of SaIntra], rOmaka siddhAnta [Doctrine of the Romans] and paItAmaha siddhAnta.
Surya SiddhAnta which had calculations on planet diameters and examples which proved that earth had multiple time zones, states that: “Objects fall on earth due to a force of attraction by the earth. therefore, the earth, the planets, constellations, the moon and the sun are held in orbit due to this attraction” See this source.
It also notably took trigonomety to the next level on sine (jya) and cosine (kojya). It states that in Chapter 3 verse 21 & 22 in this text that:
Of [the sun’s meridian zenith distance] find the jya [sine] and kojya [cosine]. If then the jya and radius be multiplied respectively by the measure of the gnomon [sundial] in digits, and divided by the kojya, the results are the shadow and hypotenuse at mid-day.
He also calculated several astronomical values which are spot on today, please google Surya Siddhanta to read the text.
IV. Vedanga Jyothisha
Of the texts that accompany the Vedas, there is one called the Jyothisha. Unfortunately, it has NOTHING TO DO WITH determining one's future! It is only a system of calendrics, and is a pure astronomy text which attempts to calculate and determine the movements of planets and celestial bodies with the goal of calculating the proper time to conduct vedic rituals. i.e. it is NOT a tool of divination. This work is said to contain approximately 36 verses from the Rig Veda and 43 verses from the Yajur Veda. This is the source of this work if you wish to read it further.
IV. Parashara Hora Shastra
This is the scripture on Vedic Jyothisha or Vedic Astrology used by most Vedic astrologers today. Please read it to get the material you need.