Tennessee Grade 4 Math

Two adjacent parts of one right angle

A ray splits a given right angle into two adjacent parts without overlap. The part beside the horizontal ray measures 35°. Let x be the measure of the other part. Write an equation, find x, and check that the parts make the full angle. Use the given measures; the display is not a substitute for a protractor task.

Follow the reasoning

A right angle measures 90°. The two adjacent parts fill it without overlap, so 35 + x = 90. Subtracting the known part gives x = 90 − 35 = 55°. Check by adding: 35° + 55° = 90°. The unknown part is larger than the 35° part but smaller than the complete right angle. The answer is an angle measure, so include the degree symbol. The equation follows from how the parts occupy the full angle, not from the lengths of the drawn rays.

Check when addition applies

The measures can be added here because the parts share the dividing ray and do not overlap inside the given angle. Adding overlapping angles would count some of the turn twice. A longer drawn ray does not make a larger angle: angle measure concerns the turn between directions. Measuring and sketching angles are related classroom tasks, but this particular example gives the measures and uses addition.

Try a changed partition

Keep the full right angle at 90° and change the known adjacent part to 28°. Write 28 + y = 90, find y = 62°, and check the sum. Explain why decreasing one part by 7° increases the other by 7° when the full angle stays fixed.

Tennessee reference for this worked activity

The Tennessee mathematics standards directory links the edition approved in February 2021 and implemented in 2023–24. The State Board’s mathematics review page identifies that edition as current through the transition to 2031–32. The linked file has a June 2022 filename and a November 6, 2020 revision footer; those dates do not identify a newly adopted 2026 edition. Use the school’s current learning sequence.

This selected reference identifies the activity focus. The complete standard and grade curriculum include additional work. These labels do not certify alignment of every independent lesson, worksheet, or quiz in the broader directory.

Choose a next task from the student’s explanation

Use a different set of numbers to check whether the student can explain the same relationship. If the explanation is unclear, return to the model; if the reasoning is sound but a calculation is wrong, work through a shorter calculation and check it against the model. Use the related learning resources alongside the teacher’s assigned goals.

The Tennessee mathematics assessment overview describes work in number sense, conceptual understanding, fluency, and problem solving, and links its assessment resources. Follow the school’s current directions and accommodations. Independently published practice has its own timing, tools, question count, and scoring; its result does not establish a state performance level. This original activity is not an official state assessment question. Read Tennessee assessment guidance.

State sources and the selected complete PDF page checked October 6, 2026. Confirm later guidance and local assignments before planning assessment preparation.