Last year, for 1st grade, our Language Arts focus was on reading. I wanted to make sure that Jay had a firm foundation for reading. We didn't do anything formal for Grammar, Spelling, or Writing. He did get Spelling and penmanship practice with the writing required in Explode the Code, which was good considering the ETC series was just review for him. We knew there was a large possibility of him having Dyslexia, which was a major driving force in my decision to hold off on the other aspects of Language Arts.
Now, we are certain that he has a very firm foundation in reading. Despite his Dyslexia, he is regularly reading (and comprehending) books at a 5th+ grade level. So, this year has more focus on other areas of Language Arts. Since this is his first year using a program for Writing, Grammar, and Spelling, I went easy on ordering. I ordered 2 levels of All About Spelling, because I was certain we would get through the 1st level fairly quickly. We haven't been doing it every day, and it is still averaging out to about 1 step a week. If we did it daily, we would definitely be further along. We'll get levels 3 & 4 next year.
I only bought one level of the Stack the Deck writing program (Discover the Deck is the level we have). I got the 2nd grade level, because he's in 2nd grade. I only bought the one level, so that we had the chance to try it out & see if we like it, before spending more money on it. He is moving through it at a faster pace than I anticipated. I'm actually having to slow him down and assign additional writing assignments, just to make this level last the year. Next year, I will be getting two levels, the 3rd grade & 4th grade levels. Even if he doesn't go through both levels next year, I'd rather have the next one if he needs it, than not have writing for 1/3 of the year.
I also only bought the 2nd grade level of Easy Grammar. I knew this would not last the whole year, but did not want to purchase more, in case he didn't like it. He does seem to like it, and is doing well with it. So, next year we'll buy the 3rd & 4th grade levels. He won't finish both next year, but we'll have Grammar for every day of our school year (one level leaves us with about 45 days without Grammar).
We also only bought one level of his Latin, Latin for Children, this year. We will continue to get just one level a year. We like to spend a little extra time and review what we're learning. So, it is taking us a bit longer to get through this. I want him to really learn the language, and I don't think he'd really learn it if we rushed through to stay on schedule.
We bought Mastering Mathematics for his Kindergarten year. It has 1st - 6th grade Math. This year was the first we've bought Math for him since then. We bought him Key to Measurement and Key to Metric Measurement, because I don't feel Mastering Mathematics covers measurement enough. Plus, he really likes measurement & is always measuring something with his ruler or one of his measuring tapes. He's currently in Defeating Division (the 4th book in Mastering Mathematics). If he keeps up his current pace, he'll be done with this book by the end of the year or in the very beginning of next year. So, we're figuring he'll be doing Perfecting the Point (decimals & percents) and Finishing Fractions (fractions) next year. We're going to buy him the Life of Fred Fraction and Decimals & Percents books. We want to see how he likes Life of Fred, and if he'd want to continue with it. So, we're going to have him do the Life of Fred books alongside the Mastering Mathematics books. That way, he gets an intro to Fred, can decide if he likes Fred, and, if he does want to continue with Fred, it will be a smooth transition from one program to another.
So, as you can see, we tend to get more than 1 level at a time. There are many reasons we do this.
One reason is that our school year is longer than a public school year. Prior to this year, I planned 40 weeks of work per school year. This year, with our new trimesters, our year is 45 weeks. A typical public school year is 36 weeks. Most programs are set up for the typical 180 day/36 week school year. Our current school year is 225 days/45 weeks (previous years were 200 days/40 weeks). That would be a fairly large chunk of the year to not have work in a subject. That would be 45 days without the subject (whichever subject we only bought one level of). 45 days = 20% of our school year.
I can deal with that for the first year using a program, while we determine if we like it, how we'll use it, and the pace the child in question moves through it. However, I wouldn't be okay with that after that first year.
The other main reason that we buy more than one level at a time is the kids. My kids are academically Gifted. They grasp & master concepts faster. They move at a faster pace. They often work above grade level; not because we skip levels, but because they get through the levels so quickly. That is just how it is. I will not apologize for the fact that my kids are Gifted, work quickly, and need extra work & challenge.
A program for 180 days means a guaranteed 20% of the school year without that subject. If they work at a faster pace than was intended & take less than 180 days, it would lead to even more of the year without that subject. I've seen them get through something in half the time. So, let's say they finished a 180 day program in half the time - 90 days. That would then be 135 days without that subject. That would be 60% of the school year without that subject.
So, between the kids' faster pace and the length of our school year, we could be looking at 20-60% of the year without a given subject, if I only bought 1 level at a time.
I buy once for the year. We don't buy as we go. I plan out what materials we will use and buy all at once. I may buy from a few places, but only when I have to. I get as much form one place as I can. Most of our materials come from Rainbow Resource. Some of our arts & crafts supplies come from Oriental Trading. There are a few other sites I may shop at for Science tools, dissection specimens, and other random items, if we really need them & can't find them elsewhere. I shop local stores for basic items like tri-fold display boards, poster boards, paper, pencils, etc. I get as much from each place as I can. By keeping the number of sites I buy school supplies from limited, I save money on shipping. The extra I would spend on shipping would have to be deducted from our school budget, meaning I'd be able to afford less of our materials. Since the budget is spent within days, I can't guarantee that I'd be able to just pick up the next level if we finish early. I really try to stick to the school budget. I could easily spend 3 times as much as I spend now. I need to make sure everything else is taken care of, too. So, I work hard to get us the right materials & the right amount of each material, all for the best price I can find.
In short, I buy so much each year because I like to be prepared, and I know my kids.