Where this sits. This is one of the four shape, data, and chance families — the middle ground, where the formula sheet does most of the remembering and your job is choosing the right formula. Every family page on this site has the same eight parts, in the same order, so once you know the shape of one you know the shape of all of them. Where a part is empty, it says so.
DrillsEleven drills for this family, one skill each, ten problems at a timeGo to the drills ↓Inches to feet, minutes to hours, quarts to cups, and the reason a square foot needs the conversion factor twice. Also reading a scale, and keeping units honest through a calculation so the answer comes out in the units the question asked for.
The test likes to hide a conversion inside a question about something else: a rate given per hour when the answer wants minutes, an area given in feet when the tiles are sold by the square yard. Catching that is most of the work.
What the test asks in this family
- Both systems, and the conversions the test usesQuiz 26
- Converting: which way the number movesQuiz 26
- Chains of conversionsQuiz 26
- Square and cubic units, and the factor used twiceQuiz 26
- Keeping units honest through a calculationQuiz 26
- Reading a scale or a gaugeReading a Scale
All 6 have something on this site.
Six questions across this family. Type an answer and press Check. You get the reasoning for every one, right or wrong.
- How many inches in 4 feet? 48. There are 12 inches in a foot, and you are going from a big unit to a small one, so the number gets bigger: 4 × 12 = 48. That is the check worth doing on every conversion — ask first whether the number should grow or shrink, and you will catch a wrong-way answer before you write it down.
- 90 minutes is how many hours? 1.5 hours. Sixty minutes make an hour, and you are going from small units to big ones, so the number shrinks: 90 ÷ 60 = 1.5. Writing it as 1.30 because it is “an hour and thirty” is the trap; time is not decimal.
- A room is 12 feet by 9 feet. What is its area in square feet? 108 square feet. Area is length times width: 12 × 9 = 108. The unit changes too — you multiplied feet by feet, so the answer is in square feet, not feet. If your answer to an area question comes out in plain feet, something went into the wrong slot.
- How many square feet in 2 square yards? 18. This is the one that catches everyone. A yard is 3 feet, but a square yard is 3 feet by 3 feet, which is 9 square feet — so the conversion factor gets used twice. Two square yards is 18 square feet, not 6.
- A car travels 60 miles per hour. How far does it go in 20 minutes? 20 miles. Twenty minutes is a third of an hour, so it covers a third of 60 miles. You could also run it as d = rt with the time converted first: 60 × 1⁄3 = 20. Putting 20 straight into the formula without converting gives 1,200 miles, which the size of the answer should tell you is wrong.
- 3 quarts is how many cups? 12. Two steps: a quart is 2 pints and a pint is 2 cups, so a quart is 4 cups, and 3 × 4 = 12. Chains like this are safer done one link at a time, writing the unit down at each step, than leapt in one go.
Missed one? Quiz 26 in Learn it below covers both systems, the conversions the test actually uses, and the square-unit trap. Reading a Scale under On paper covers rulers, thermometers, cups and dials.
Want more than these six questions? Flyover I asks about all fourteen families in one sitting and ends in a grid that says where to start; Flyover II asks them again later, with different questions, so you can see what has moved.
- Quiz 26Units and ConversionsBoth systems, the conversions the test uses, and how to keep them straight.
This is the first quiz of the Okapi Series. One quiz covers the family for now; more will follow.
Eleven short drills, one skill each, in order. Each starts with two worked examples, then gives you ten problems (or five) and the reasoning for every answer. Each one prints, with the answer key on the last page. When you get all ten right, or all five right twice in a row, the drill gets a check mark on the Drills page.
- 6.01Length: inches, feet, yards, miles · calculator allowed
- 6.02Weight: ounces, pounds, tons · calculator allowed
- 6.03Capacity: cups, pints, quarts, gallons · calculator allowed
- 6.04Time: seconds to days, and elapsed time
- 6.05Metric units: kilo-, centi-, milli-
- 6.06Add and subtract mixed units (5 ft 8 in + 2 ft 7 in)
- 6.07Convert a rate (miles per hour to feet per second) · calculator allowed
- 6.08Read a ruler to the nearest sixteenth of an inch
- 6.09Read a scale: cups, thermometers, dials
- 6.10Use a conversion formula (Fahrenheit and Celsius) · calculator allowed
- 6.11Unit word problems · calculator allowed
No app for this family yet.
- Reading a Scale · rulers in eighths and sixteenths, thermometers above and below zero, measuring cups, dials and gauges, and number lines with only the ends labeled. One method for all of them, 21 problems, answers at the end. Made to print.
- Khan Academy, math · free videos and practice. Search it for unit conversion, converting units of measure. These are the clips we start from in class.
- Math Antics · short, plain videos on the basics.
- Light & Salt Learning · free GED classes online, with playlists by topic.
- Get Sum Math · GED math on video, one topic at a time.
- Kaplan GED Test Prep and the McGraw-Hill Mathematical Reasoning Workbook · look up measurement and units in the contents of either.
On to geometry — the biggest family on the test, and the one most students have seen least. Units come with you: every perimeter, area, and volume answer has a unit attached, and the test checks it.