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Well, the standard 5.MD.1 simply asks students to convert … it doesn’t say whether they should memorize the relationships. That said, my own opinion is that there are some basic relationships that students should simply know, for example that there are 12 inches in a foot. It seems a waste of time to look this up in a chart when the human brain is already naturally adapted to storing such bits of information. Whether they acquire this by memorization or by repeated exposure is a matter of pedagogy, not specified in the standards. And the metric system is designed for ease of remembering.
Once you have a few basic facts, you can derive the others. For example, if you know there are 100 centimeters in a meter, you also know that a centimeter is 0.01 meters; it is not a separate fact, but a related fact coming from and understanding of the relationship between multiplication and division and an understanding of decimal notation.
1) The standard says “Focus on constructing triangles from three measures of angles or sides, noticing when the conditions determine a unique triangle, more than one triangle, or no triangle.” You can notice experimentally that two angles determine the triangle without knowing the angle sum theorem. In fact, noticing this is good preparation for the angle sum theorem, since it makes you suspect that something like it might be true. There’s also no harm if it comes up; it’s just not required until Grade 8.
3) I think you’ve answered your own question here; certainly describing the cross-sections in 7.G.3 would benefit from drawing figures in 7.G.2. I think 7.G.2 is mostly about plane figures.
2) Have you considered connecting it more to the algebra part of the curriculum? It’s a good opportunity to work with equations.
A couple of thoughts on this. First, 4.MD.1 is about converting from larger units to smaller units, not the other way around. Converting both ways is in 5.MD.1, which in fact mentions as an example the exact conversion you give, 5 cm to 0.05 m. The reason for this is that multiplication of whole numbers by fractions doesn’t occur until Grade 5. However, you are right that this particular conversion could be discussed in Grade 4, using both 4.NF.6 and 4.NF.4, which enables students to see 5/100 as $5 \times 1/100$. Still, it is not required in Grade 4. And your second example is even less required!
Partly it is just a matter of the level of sophistication with which the topic is treated. But notice also that the high school standard makes explicit reference to population parameters, whereas the Grade 7 standard simply talks about gaining information about the population. So in Grade 7 you might just look at a graphical representation of the sample and discuss what you can infer from it, whereas in high school you get more into the technical details of estimating parameters such as mean and standard deviation.
Mixture problems are certainly among the problems you might give students in Grade 8 working with simultaneous equations. But I think you have be clear in your own mind what the purpose of doing so is. If mixture problems occur among a range of problems where students have to model a situation by setting up a system of simultaneous equations, solve the system, and then interpret their solution, then that’s good. If the idea is to have a separate unit called “mixture problems” where you look at a lot of problems following a fixed template, and train students in a fixed procedure for dealing with that template, then that’s bad. It’s not the type of problem that is important, but learning flexible skills and understandings that can be applied to other types of problems with the same structure that are not about mixtures.
Yes, those are in the works. But I’ve given up on timelines, since I never meet them! I will say that they are basically ready in draft form and just need some formatting and checking.
