Each problem is a drawn number line with an arrow over one tick, and the question is always the same: what number is the arrow pointing to? The lines mix whole numbers, integers and fractions, so a student has to read the scale before reading the mark.
Not every tick is labelled. On a longer line the labels come every fifth or every second tick, so reaching the arrow means counting on from the nearest one - which is the part of reading a number line that actually takes practice.
Seeing where a number sits relative to others. It is how ordering, rounding, negative numbers and fractions are all introduced, because it turns an abstract value into a position.
Because a mark between ticks has to be estimated, and two students can read it differently and both be reasonable. Every question here has one right answer.
No, and that is deliberate. An answer that is a mark on a line cannot be printed in an answer key - it would have to be a second drawing for a teacher to compare against. These ask students to read a line, not to mark one.
Second grade upward for whole numbers, third for fractions on a line, and sixth for integers. Choose the type under Number line to match.