RightStart Geometry

The continuing saga of our adventures using RightStart Geometry and RightStart B. I have an 11yo and a 7yo who have average math ability.The 11yo has done Miquon, Singapore, RightStart Transitions, Level D and Level E; RightStart has saved her from a life a math phobia.

I try to update our adventures on Tuesdays, although sometimes it doesn’t get done until Wednesday. And sometimes we really haven’t done that much math, so I skip it entirely.


RightStart Geometry:

Lesson 116 Cross Multiplying on the Multiplication Table

I didn’t realize there was a term for this idea of cross-multiplying. What it refers to is looking at a multiplication table for 1x6 and 3x2; now, if you draw a line between the 1 on the first line and the 6 on the second line (showing you’re multiplying them), then draw a line between the 2 on the second line and the 3 on the first line (showing you’re multiplying them), you’ve made a big X.

Various applications are given. For example, mental multiplication can sometimes be easier with cross-multiplication: 8x35 forms a cross with (and therefore has the same answer as) 20x14. (I’ve gotta admit, though, I would never, ever mentally multiply 8x35 that way...I might factor it out a bit and make it 40x7, but probably I’d just do 8x30 plus 8x5 and move on with my life; however, MrV is much quicker at mental math than I, and I wonder if he’s using this technique at times.) Another application is in simplifying proportions.

Lesson 117 Measuring Heights

You know, if I weren’t reviewing every single lesson in this Appleworks file, I might never have realized that this lesson called for a small mirror and a sunny day. Yoohoo, that didn’t happen around here -- no mirrors or sunny days were used to measure the height of something tall outside (tree, pole, building). Hmmm.

Lesson 118 Golden Ratio

KidV1 despised this lesson, and managed to spend the entire day on it. Really, it’s just a matter of calculating phi to a couple of digits, then working with it a bit. It’s hard for me to help her, as her worksheet it so covered with doodles that I can barely see the problems.

Among the issues: she announces that she likes the “other rectangles” better than those that are golden rectangles. She finds them more pleasing. Sigh. How to explain centuries of design theory in about 5 minutes and (possibly) motivate her? I explain that the ancient Greeks used the Golden Ratio in their architecture (she’s currently fascinated with the Greeks), I google pictures of buildings both ancient and modern, I find a page on web design that explains how to use Golden Rectangles to make customer-pleasing design, we look at phi to 1000 decimal places (weird numbers are also interesting). In the end, though, it’s just a matter of “This Must Be Done. Period.”

Really, she has great talent for engineering and architecture, so it’s annoying that she hates this so. I console myself with the thought that perhaps she’ll be a groundbreaking designer that will find a new proportion that will revolutionize design theory.