1. Will students' scores on an achievement test differ between directive teachers and non-directive teachers?

2. Are students aged 55 and older more likely to drop out of college than students of ages between 30 and 40?

3. How do three counseling techniques—rational-emotive, gestalt, and no-counseling—differ in their effectiveness in decreasing test anxiety in high school juniors?

4. The main purpose of this study is to compare the effectiveness of two reading methods, sight and phonics, in increasing verbal comprehension.

5. The study investigated whether the ability to discriminate among parts of speech increased with chronological age and educational level.

Answers

1. Will students' scores on an achievement test differ between directive teachers and non-directive teachers?

IV: teaching style which has two categories, directive and non-directive (qualitative--two distinct categories)
DV: scores on achievement test (quantitative--scores on tests usually range from 0 to 100 and therefore can be ranked from high to low)

In this example teacher is not a variable since we are only referring to teachers, so teacher is a constant. What does vary is teachers' style of instructing (directive vs. non-directive) and it should be clear from the statement that how directive one is affecting student learning.

2. Are students aged 55 and older more likely to drop out of college than students of ages between 30 and 40?

IV: age, with two categories, 55+ and 30-40 (qualitative--two categories; if you said quantitative you are right too since these categories can be ranked from high to low, but since only two categories, simply treat as qualitative)
DV: dropout, with two categories in or out (qualitative)

3. How do three counseling techniques—rational-emotive, gestalt, and no-counseling—differ in their effectiveness in decreasing test anxiety in high school juniors?

IV: counseling techniques, with three categories, rational-emotive, gestalt, and no-counseling (qualitative--three distinct categories that cannot be inherently ranked ordered)
DV: test anxiety (most likely quantitative--since test anxiety varies by degree, no kind, that means that each category of test anxiety can be ranked or sorted from more to less anxious)

4. The main purpose of this study is to compare the effectiveness of two reading methods, sight and phonics, in increasing verbal comprehension.

IV: reading methods, with two categories, sight and phonics (qualitative)
DV: verbal comprehension (most likely quantitative since measures of verbal comprehension will be some type of achievement test which allows one to sort people by how much they comprehend or achieve)

5. The study investigated whether the ability to discriminate among parts of speech increased with chronological age and educational level.

IV: age and educational level (most likely both are measured in a quantitative fashion with age indicated by actual years--1, 2, 3, 4, etc.--and educational level indicated by level of schooling like some high school, high school graduate, some college, college graduate, etc. While these levels of education are not precise, they can be sorted by amount of education and therefore represent an ordinal variable.)
DV: ability to discriminate among parts of speech (most likely a quantitative variable. Most people, when faced with the word ability, think of something that varies from person to person and note that some people have more of it than others. This suggests at least an ordinal variable, hence it is quantitative.)