The last time I went looking for a large tin of Active Dry Yeast, my supplier didn't have any. Instead of the big blue and white tins that I've been buying for a couple of years, they had little square packages of Instant Active Dry Yeast. As I was almost out of yeast altogether, I bought the instant. Now. How to measure it? God bless Google. I found good information at "The Artisan".
And as a quick reference for myself:
2 1/2 teaspoons Active Dry Yeast = 2 teaspoons Instant Active Dry Yeast
1 7/8 teaspoons A.D.Y. (let's say 2) = 1 1/2 teaspoons I.A.D.Y.
1 1/4 teaspoons A.D.Y. = 1 teaspoon I.A.D.Y.
Using the first conversion as a base, 1 Tablespoon Active Dry Yeast would equal 2.4 teaspoons Instant Active Dry Yeast; so, when making cinnamon buns or bread recipes calling for 1 package, (which is a scant Tablespoon) Active Dry Yeast, I'll use 2 1/2 teaspoons Instant Active Dry Yeast.
And Glory, Hallelujah! The Yeast is Converted.