Measuring Objects Using Customary Units Unit of Study 8 : Measuring Length and Perimeter Global Concept Guide: 1 of 3
Content Development Approximately 5 days should be spent on measuring to the nearest whole, half, and quarter inch. The jump from measuring with nonstandard units (second grade) to using standard rulers is challenging. One of the best methods of helping students understand rulers is to have them make their own rulers out of actual units. (Van De Walle, 2010, p.375) When measuring to the nearest inch make sure students understand that lengths more than halfway between two inch tick marks should be recorded as the next whole inch. Lengths less than halfway between two inch tick marks should be recorded as the previous whole inch. Allow students to measure real objects rather than just pictures on paper. Use rulers with the zero mark a short distance from the edge. This tool will force students to think about both endpoints when measuring and to focus on units when they measure.
Day 1 The focus of Day 1 is making a ruler. To access students prior knowledge of appropriate units of measure, see Unlock the Problem on p Students should make their own ruler before measuring with an actual ruler. Provide each student with a set of 2 different colored color tiles. (The set should consist of six of both colors.) Each student will also need a long piece of tag board (or a sentence strip) that is 13 inches long and two inches wide. Students place the color tiles in alternating colors along the top of the tag board, leaving a small white space before the first segment. Segments should touch each other, but not overlap. After tracing each segment and coloring it in, students can measure objects with their ruler.
Day 2 The focus of Day 2 is measuring to the nearest half inch. Adding to the student created ruler: Give each student a piece of tag board that is one inch by one inch (the size of a color tile) and have them fold it in half and cut on the fold. (You may want to have some spare pieces that are already pre-cut into halves and fourths for students that have difficulty folding and cutting). Using the two halves, students will mark the half inch marks on each of their segments. They should check for accuracy using their two cut pieces. Students can measure objects to the nearest half inch with their ruler. Misconception Alert: Students may view the process of measuring as a procedural counting task, for example students count the marking on a ruler (rather than the units), resulting in an incorrect measurement of length.
Day 3 The focus of Day 3 is measuring to the nearest quarter inch. Adding to the student created ruler: Repeat Day 2, but with fourths (Cut the halves in half to make a total of four pieces). Mark the fourths on the student rulers. It is important that they cut both halves to make a total of four congruent pieces for the whole (fourths). Students label their rulers in a way that is understandable to them. Rulers should begin with “0” and end with “12”. Students can measure objects to the nearest quarter inch with their ruler.
Day 4 The focus of Day 4 is measuring with a standard ruler. Students can compare their own ruler to a standard ruler. Students can makes estimates and measure objects to the nearest quarter inch with a standard ruler. (See Fun with Fractions Illuminations lesson; Inch By Inch Activity Sheet: Part II)
Day 5 The focus of Day 5 is measuring with a broken ruler. A broken ruler is a ruler than does not start at zero. Example: What is the length of the pink line below?
Day 5 By the end of Day 5 Students Should be Able To Generate appropriate estimates Measure to the nearest quarter, half, and whole inch Measure with a “broken” ruler
Enrich/Reteach/Intervention Reteach: Allow students to continue to use the rulers they created until they are ready to move to the standard ruler. Allow them to continue to measure small sets of real world objects. You can also utilize R96 & R97. Enrich: TE 469B Draw lines to match riddles/descriptions given.
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