• Exercises 1-4 are designed to put you through the paces of identifying noun forms, especially 'cases' -- and all the ways they are described, built, and taken apart.
• 1. This exercise is a matter of finding the formula: take the athematic noun endings from earlier in the chapter and apply them to the forms given to figure out whcih one matches.
  
• 2. This is the same as exercise 1, but uses a thematic (o-stem) noun: find the chart earlier in the book and match the forms given here to that chart. When you can't find a match, read the explanation after the chart. The chart in question is at 6.45, and the information that will help you identify 2a is in the explanation of the genitive singular at 6.48.
• 3. This one is the reverse of the above: this time, use the chart at 6.45 to build the forms in question. Take the stem and add the indicated ending.
• 4. This is the same as #3, but asks for all the forms instead of particular ones.
• Exercise 5 is a more abstract one: it asks you to apply a pattern to individual forms and see which part of the pattern work for each form.
  
• 5. This one asks you to use the charts
•  at 6.20. It is important to know that the nominative and accusative are the "strong" forms in the upper half of the charts, and the genitive is one of the "weak" forms in the lower half of the charts. This is highly abstract and so may seem more "mathematical."
• Exercise 6 and 7 asks you to learn some of the suffixes used to build nominals and what they mean.
• 6. This is a hunt-and-identify exercise: you need to hunt through the chapter to find the indicated ending that has been added to the verb stem to produce a noun. Each ending has a meaning.
• 7. This is the reverse of 6: find the ending with the indicated meaning and build a noun with that meaning out of the noun you are given. As a side note: here you are deriving a nominal from a nominal: in 6 you were identifying a nominal derived from a verbal.
  
• This is a critical thinking exercise asking you to do what a PIE specialist does when trying to figure out a pattern.
  
• 8. This exercise asks you to find a pattern in a given set of forms: the aim is to find what is different about the forms that are build with a *-u- from those that are built with a *-ro-. That difference is found in the stem before the *-u- or *-ro-.
• This one is about compound words made up of two stems: not a stem + suffix + ending, but rather two stems, called a "compound word."
• 9. This exercise asks you to apply the information about compound words found in 6.82-86.
  

Some answers

• 6.
  
• a. 6.34 n-stem athematic: neuter abstract noun suffix *-mn (that n is syllabic: I can't find the symbol for n with a circle under it right now): creates a nominal referring to the action or result of the action of the root meaning.
  
• b. 6.37 r-stem agent suffix *-ter and *-tor: the noun names a doer of the root action.
  
• c. 6.38 s-stem athematics having •-os  in the strong cases and *-es- in the weak cases: they are verbal abstract nouns, so they are a nominal for the action of the root. Here, we predict a meaning of perhaps 'speech' or 'word'
  
• d. 6:59 thematic Tómos v. Tomós: add *-os to an o-grade root, and you get either an agent or action word (accented on the *-os) or a result of an action word (accented on the root).
  
• e. 6:67 thematic nouns for tools in *-tlo-/*-dhlo-/*-tro-/*-dhro-
  
• 7.
  
• a. this is athematic : from what I can tell, add the feminine suffix *-eh₂-, or maybe just *-h₂-: see Fortson 6.68-70: wikipedia's Proto-Indoeuropean Nominals article has a small section on gender that may help too), but looking at 6.71, it is more likely to be -ih2
  
• b. use info from 6.70 (I think: this is not made absolutely crystal clear by Fortson): take *h₂ŕ̥tḱos, take off the thematic *-os ending (6.58 says this word is thematic) and add a feminine suffix *-eh₂-, or maybe just *-h₂- (see 6.68-69 and first full paragraph on P. 133)
• c. this one is probably trying to get us to go to 6.73 about adjective formation. We find nothing that particularly applies to *smókr (it is not obviously an i or u stem and the rest of the paragraph doesn't tell us how to form an adjective from just any old stem), but then we notice the last sentence which tells us that athematics can form adjectives by "internal derivation."
• So we go to 6. 29:
• *smókr looks like it is an acrostatic noun: it has an accent on the first syllable which is also o-grade (those two traits are unique to acrostatics according to the chart at 6.20.
• and acrostatics can be turned into proterokinetics by creating a noun with the following pattern
• strong cases: accent the stem but make it e-grade stem, and leave suffix alone
  
• weak cases: make the stem zero-grade,  accent the suffix and make it e-grade
• so we get *smékr. with weak case stem *smkér
  
• 8. Hint: look at the vowels in the root (the first item given for each line).
  
• 9. A simple question identifies an endocentric compound: ask the following question about each of the two parts of the word: "Is the thing named by this word a _____?" If the answer is "yet" to either, it's an endocentric term. If it is 'no' to both, it's exocentric.
• Examples
• doghouse: is it a dog? no. Is it a house? yes (I know, it's not a house for people, but it's a kind of house). So it's endocentric.
• roughneck: is it a rough? no. Is it a neck? no. so it's exocentric.