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Blood and Guts covers the major body systems and has a nice handful of experiments and activities to do, including dissections. The physiology is good, though the simple line drawings don't really capture anatomy well.
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Books well written in an engaging style such that they are an enjoyment to read;
Books with high quality information, both in morality and depth.
The industry is clearly more excited about glossy photography and eye-popping illustrations than it is about content and writing. What concerns me most about content is that the middle school literature contains little more depth than the elementary literature, and is thus far behind high school textbooks.
You can search the Massachusetts Curriculum Frameworks (standards) by grade and subject. I compared the grades 6 through 8 standards with those for high school. Is it my imagination or does there seem to be a huge gulf between them? Perhaps I should start eyeing those high school standards more often and searching for books that will bridge that gulf.
A good way to get living books is to be quite specific about a topic. While a search for "ocean" is apt to get you a whole lot of twaddle, looking specifically for "tides" or "currents" will more likely turn up something more in depth and engaging. Don't be afraid of "feeding" your children these advanced concepts. Just like literature, children "hunger" for interesting learning. Don't settle for the Great Illustrated Classics version of science!
First let me mention Homeschool Buyer's Co-op. They arrange group discounts from various companies for their members, and membership is free. Discount amounts go up as more members purchase a product.
They have a lot of science offerings, some of which have purchased.
Currently they are offering discounts on several Bolden microscopes through October 13th. Only now that all of them have reached the maximum discount are they worth the price. Shipping is $15 per scope.
My First Lab Microscope, now down to $83, is comparable with Kids' Microscope at Home Science Tool for $95. No fine focus. The optics are O.K. (some of my biology students use this model.) It will do the trick.
The Premiere Student Microscope, now at $131, is comparable with Great Scope's SF3 for $149. The SF3 has fluorescent lighting but no coaxial focus ($179 for that option.) Bolden is also offering a cordless version with LED lighting now at $137.
The Premiere Advanced Student Microscope, now at $197, gets you the 100x oil immersion lens and a mechanical stage along with the coaxial focus nobs. Bargain Microscopes has a $175 model with the 100x lens, but without a mechanical stage (a very nice feature costing $25 at Home Science Tools) or coaxial nobs (makes little difference to me.) Bolden's LED cordless version is $203.
Next closest model is Great Scope's SF4 for $209 (+$10 shipping) with coaxial nobs and fluorescent lighting; add a mechanical stage and the price goes up to $248. Home Science Tool's comparable model is $240 with a mechanical stage and fluorescent lighting.
I actually needed a few extra small struts--these, too, maintain the golden ratio in relation to the other struts. I didn't have enough struts to make the second wing.
The website and kits have a wide range of geometric models, from simple Platonic solids to a complex taurus (doughnut) and even a large DNA model. You can download a set of challenge cards, or lesson plans for grades 1 through 12.
This makes a great math and science manipulative especially if your kids like to build like my boys do. Their imaginations are their guides!