"They shall place upon it [the aron] a tachash-hide covering, and spread a cloth entirely of turquoise wool over it... upon the table of the show-bread they shall spread a cloth of turquoise wool... and cover it with a tachash hide" (BAMIDBAR 4:6-9).

These were the instructions given to Aharon how to prepare the utensils of the Mishkan for travel. Generally, the kohanim used a woolen covering and a leather covering. There is one discrepancy between the aron and the other utensils. The other utensils, such as the shulchan and menorah, were fi rst covered with a turquoise cloth and then with the tachash-leather covering. The aron, however, was fi rst covered with the tachash-hide and then with the turquoise wool covering. What was the reason for this diff erence?
The Netziv explains that the turquoise represented Divine Providence. The color blue reminds us of the sky, which in turn reminds us of Hashem's Holy Throne. The tachash-leather, on the other hand, represented the physical world, similar to leather used as a protection from the elements. Each of the utensils in the Mishkan represented a different quality. For example, the shulchan symbolized kingship and wealth and the menorah represented Torah knowledge. Although succeeding in these areas ultimately comes from Hashem through Divine Providence, success appears to result directly from our actions. Good decisions and good judgment bring to wealth and leadership, and success in Torah knowledge results from learning diligently. We ascribe success to the aforementioned factors because this is what we see in our limited view of the world, but in reality, it all comes from G-d. The Torah dictated to place the turquoise covering directly on the utensils and the leather covering on top of that, to signify that although it appears that our physical actions produce the desired results, it really comes from Hashem. The order of the coverings was switched for the aron, because the aron represented the Torah itself. The Torah has some obvious aspects and some aspects that are not so obvious. It was clear to all that the Torah was G-dly. The Aron miraculously carried those that held it, and at Har Sinai, it was clear that Hashem gave the Torah to Moshe. However, it is not so clear that buried within the wisdom and secrets of the Torah is the success and sustenance of the entire world. To show this, the Torah commands to cover the aron on the outside with the turquoise covering, showing that the Torah clearly came from Hashem. Covering the aron on the inside was the tachash-leather, which was hidden, representing that even the success of the other physical aspects of our lives result from the Torah.
Why Now?
The Jewish calendar is set up in such a fashion that we always read Parshas Bamidbar the Shabbos before Shavuos. Why? The Rishonim argue if the Mishkan was built solely to atone for the sin of the Golden Calf, or the Mishkan was built in its own right, regardless of the Cheit Ha'Eigel. Ramban is of the opinion that Hashem always intended for the Mishkan to be built to serve as a microcosm of Har Sinai. At Har Sinai, Hashem revealed Himself and we experienced His presence. Similarly, the Mishkan was a place for us to experience G-d's manifestation. Based on this idea, Ramban, in his introduction to Sefer Bamidbar, explains a reason for the formation of the Jews' encampment around the Mishkan. At Har Sinai, Hashem set boundaries around the mountain, commanding the Jews that they cannot encroach past the set borders. Similarly, Hashem established different camps around the Mishkan, marking where pure and impure people may reside. Another similarity is that at Har Sinai, Hashem chose the fi rst-borns to bring sacrifi ces and perform the service; in the desert, He chose Shevet Levi to serve Him. All these laws and precautions were implemented in order to maintain the sanctity of the Mishkan, a replica of Har Sinai. Possibly, we read Parshas Bamidbar before Shavuos in order to draw parallels between Har Sinai and the Mishkan. Just as Klal Yisroel witnessed G-d's revelation on Har Sinai, we will witness His revelation at the Bayis Shlishi, bimhayra bi'yameinu.