# 3rd Grade - Measure Length And Volume

 Grade Level: 3rd Skill: Problem Solving Topic: Measure Length and Volume Goal: Choose the appropriate tools and units (metric and U.S.) and estimate and measure the length, liquid volume, and weight - mass of given objects. Skill Description: Measurement and Geometry: estimating and measuring length, liquid volume, and weight/mass of object The ability to choose and use an appropriate measuring device and to make a reasonable guess as to the outcome before completing the measurement.

## Building Blocks/Prerequisites

### Sample Problems

 (1) How do we know whether to use pounds, inches or quarts? (It depends on what you are measuring, weight, length or volume) Length: 1 foot (ft.)= 12 inches (in.); 3 feet = 1 yard Weight/Mass: There are various systems of weights around the world. We use: 1 ounce = 16 drams; 1 pound (lb.) = 16 ounces (oz.); 1 ton (tn.) = 2000 pounds. Volume: 1 gallon = 4 quarts; 1 quart = 2 pints; 1 pint = 2 cups (2) The metric system is based on the decimal system and used by 95% of the world’s population. What is the meter? The standard unit of length in the metric system is the meter (m). 1 millimeter (mm) = 0.001 meter, 1 centimeter (cm) = 0.01 meter (m), 1 decimeter (dm)= 0.1 meter, 1 kilometer (km) = 1000 meters (3) How does a meter compare with the U.S. yard? 1 meter is a little longer than 1 yard (3 ft). It is about half the height of a very tall adult. A cm is a little less than ½ inch and about the diameter of a dime. A mm is about the thickness of a dime. (4) What is a liter? The standard unit of volume in the metric system is the liter (l). One liter = 1 cubic cm in volume. 1 milliliter (ml) = 0.001 liter, 1 centiliter (cl) = 0,01 liter, 1 deciliter (dl) = 0.1 liter, 1 kiloliter (kl) = 1000 liters. 1 liter is a little more than a quart and 1 teaspoon = about 5 milliliters. (5) What is a gram? The standard unit of mass in the metric system is the gram (g). 1 milligram (mg) = 0.001 gram, 1 centigram (cg) = 0.01 gram, 1 decigram (dg) = 0.1 gram, 1 kilogram (kg) = 1000 grams (g). 1 gram is about the weight of a paper clip and one kilogram is about the weight of a liter of water.

### Learning Tips

 (1) Have children cut out a 1-inch rectangle of paper and fold it in half. Ask your child how long he/she supposes that the folded half measures and listen to his/her reasoning. If necessary, explain that this is ½ inch. Fold the paper again and see if your child knows how to name this new measurement; again, if necessary, explain that that size is ¼ inch. Prompt them to count how many half-inches made the whole inch and how many ¼ inches made the whole inch. Also, show these measurements on a ruler. (2) Have children practice measuring items around the house with the ruler. Have them guess how long an object will be before measuring. Children can do this in standard and metric. (Note: children do not always know that in order to measure accurately we must start with the 0 on the ruler at one end of the item to be measured. Point out, if you have such a situation, that not all rulers/tape measures begin with 0 at the every end of the measuring tool and if that is the case, be sure that the 0 mark is your starting point.) (3) After children are skilled at measuring with a ruler, have them measure scale drawings that you, or they, draw on paper. For example, draw a flowerbed with various types of flowers. Children can measure the dimensions of the bed, as well as the spaces occupied by each type of flower. Make sure your measurements are exact to make it easier for students to be precise. Similar activities can be done with a yardstick or a piece of string cut to the length of a yardstick. Water play with a purpose can help students understand volume as they pour water into various sizes of container. For weight, children can hold a pound of sugar or other kitchen item in one hand and a five pound bag of food or other in the other hand. Students can hold pencils, staplers, and other household items and begin to estimate weight. The same types of activities can be done using metric forms of measurement. (4) Have children estimate the measurement of many different lengths of strips of paper and then measure them with the ruler. Have children measure their own height and then help them measure it with the yard string and ruler. Choose items around the house and ask students what tool he/she would use to measure the object. (5) An appropriate cutting activity can be introduced that is fun for children, builds small-motor co-ordination and, once learned, can use up a block of time when an independent activity is desirable: Start with a half-sheet of paper (easy to handle, but really, any size will do) and with age-appropriate scissors, start cutting at one corner. Cut, parallel with the edge of the paper, the thinnest strip that the child can manage. With practice, children become more skilled at cutting a thin strip. When the child reaches the paper’s corner, have the child carefully turn the corner with the scissors, being careful to not break the cut piece. Continue around and around the sheet of paper, allowing the cut strip to get longer and longer. The goal is to have it remain in one continuous strip until your child has cut all the way to the center of the paper and cannot turn the paper to cut it again because the uncut part is too small. With a partner, very carefully stretch the long strip of paper out just as far as possible to reveal its length. It won’t be perfectly straight (all those rounded corners!) but it will be possible to measure how long the strip is. (This is a lot of “work” for a child, so if the paper breaks, fasten with tape so the activity can continue.) Very likely your child will be very surprised at the length of the strip he/she has been able to produce. Try it again, using different sizes of paper, trying to cut thinner and thinner strips, estimating before measuring whether or not the new strip is longer than a previous attempt, etc. Measurements can be made using different tools and scale—tape measures, rulers, carpenter/household measuring tapes, etc. in either centimeters or inches. If you have a household measuring tape (they usually pull out from the center of a metal case) introduce your child to the concept of a measuring tool that is marked in both inches and feet.

### Online Resources

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### Extra Help Problems

 (1) Circle the best estimate of the weight of a newborn baby in standard U.S. measurement: 1 lb, 8lbs, 20 lbs or 25 lbs. (2) Estimate the length of a pencil. (approx. 8 inches) (3) Estimate the weight of a small dog. (approx. 15 lbs) (4) Estimate a bathtub full of water. (approx. 50 gallons) (5) What is the best unit of measurement to measure the length of a surfboard? (m) (6) What is the best unit of measurement to measure a highway? (km or miles) (7) What is the best unit of measurement to measure the height of a door? (yards or meters) (8) What is the best unit of measurement to measure a can of soda? (ounces) (9) If you were in England, what type of measurement would be on your bathroom scale? (metric measurement for mass/grams, kilograms) (10) If you were in the United States, what type of measurement would be on your bathroom scale? (pounds) (11) About how much mass does a paperclip have in grams? (1 gram) (12) Look at the packaging of several food items in your kitchen. Write down the form of measurement that appears on the packaging and the amount. In other words, write the item and note its weight, volume or length depending on the product. (13) How much does a liter of water weigh? (about a kilogram) (14) How thick is a dime if using the metric system? (about 1 mm) (15) How wide is a dime if using the metric system? (about 1 cm) (16) Is a cm more or less than ½ inch? (less) (17) About how many ml are in a teaspoon? (five) (18) Write the abbreviations for meter, centimeter, and kilometer. (m, cm, km) Write the abbreviations for inches, feet, and yards. (in, ft, yd) (19) Write the abbreviations for liter, milliliter, deciliter and kiloliter. (l, ml, dl, kl) Write the abbreviations for cups, pints, quarts and gallon. (c, pts, qt, gal) (20) Write the abbreviations for gram, milligram, kilogram. (g, mg, kg) Write the abbreviations for ounces, pounds and tons. (oz, lb, tn) (21) When is it appropriate, do you think, to use the metric system and when is it best to use the standard system we often use in the U.S.? (answers will vary, but children might say that it depends on what country you’re in or what other people will be sharing your measurements or for what purpose you’re measuring.) (22) What number is the metric system based on? (10) (23) What number is the standard United States system based on? (12) (24) How much of the world uses the metric system? (95%, the U.S. is the only industrialized country that does not use it) (25) Estimate your weight and then step on a scale if you or one of your neighbors has one to see how close you were. Try to convert that weight to an approximate weight in kilograms.