Standing Kicks and Memorized Forms

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Standing Kicks and Memorized Forms

Use balance and practice data to trace signals from receptors to the brain.

The balance test

Read the passage and Table 1, then answer the questions.

Balance Check at the Studio

1Valentina Kruger, a sixth grader, has a yellow belt in taekwondo. Many taekwondo kicks are done while standing on one leg, so Master Kalinda Reyes, who teaches Valentina's youth class, checks her students' balance each season. The studio, the people and the numbers here are made up, but they are based on real balance and learning studies.

2Master Reyes explained that keeping your balance depends on signals from several kinds of sense receptors. The eyes detect light and show where the body is compared with the room. Balance organs in the inner ear detect when the head tilts or moves. Pressure receptors in the skin of the soles detect how weight presses on each part of the foot. Stretch receptors in muscles and joints detect how far each joint is bent. These receptors send signals along nerves to the brain, which combines them and sends signals to muscles to correct a wobble. A thick, soft foam pad squishes and shifts under the foot, so the signals from the soles and ankles become much less useful.

3For the test, 12 students stood on one leg with their hands on their hips. Each student did 3 trials in each of four conditions. A trial ended when the raised foot touched down, the hands left the hips, or the timer reached 30 s. An adult stood beside each student, and mats surrounded the foam pad.

4In the fall, the class also began learning a new form, a set pattern of 18 blocks, kicks and steps done in order. Master Reyes counted each student's errors (a wrong or missing move) in several practice sessions. From Session 4 on, students also did the form once with their eyes closed. After Session 8, the studio closed for a three-week holiday break. On the first day back, she tested the form again before any practice.

Table 1. One-Leg Balance Test (mean of 12 students, 3 trials each)
Condition	Eyes	Surface	Mean time (s)
A	Open	Hard floor	29
B	Closed	Hard floor	15
C	Open	Foam pad	25
D	Closed	Foam pad	6

1.

Use Table 1.

Closing the eyes cut the mean time by s on the hard floor and by s on the foam pad.

2.

Why did Master Reyes average 3 trials for each student in each condition?

A. So the students would be tired before the foam padB. So the hard floor had time to warm upC. So each student could watch the others firstD. So one unusual trial would matter less

3.

In Condition B, which sense receptors were still sending useful signals about the body's position?

A. Taste receptors and smell receptorsB. Light receptors in the eyes and foot pressure receptorsC. Inner ear, foot pressure and muscle stretch receptorsD. Light receptors in the eyes and inner ear receptors

4.

Condition D gave by far the shortest times. Which explanation fits paragraph 2 best?

A. Closing the eyes switched off the balance organs in the inner ear.B. The foam pad tired out the leg muscles during the first trial on it.C. With eyes closed and the foam blurring foot signals, the brain had mainly the inner ear.D. The foam pad sent extra-strong pressure signals that drowned out the eyes.

5.

During a kick, Valentina starts to tip to the left and catches herself. Which order of events is correct?

A. The leg muscles detect the tilt → the muscles shift her weight → nerves tell the brain afterward what happenedB. Receptors in the inner ear and soles detect the tilt → nerves carry signals to the brain → the brain signals the leg muscles to shift her weightC. The brain signals the leg muscles → receptors in the inner ear and soles detect the tilt → the muscles shift her weightD. Nerves carry signals from the brain to the inner ear → the inner ear shifts her weight → the soles detect the change

6.

A classmate has an inner-ear infection that makes his balance organs send faulty signals. In which condition would his brain have to depend most on those faulty signals?

A. Condition D, where neither his eyes nor his feet help muchB. Condition B, where his feet still send useful signalsC. Condition C, where his eyes still send useful signalsD. Condition A, where his eyes and his feet both send useful signals

Learning a new form

Use paragraph 4 and Table 2.

Table 2. New Form: Mean Errors per Student (18 moves)
Session	Errors, eyes open	Errors, eyes closed
Session 1	8	not tested
Session 4	3	6
Session 8	1	2
After the 3-week break	2	3

7.

Use Table 2.

From Session 1 to Session 8, the mean number of errors with eyes open fell by errors.

8.

After the three-week break, errors with eyes open went up only from 1 to 2. What does this suggest best?

A. The form was stored in the leg muscles, which grew stronger over the break.B. The form was stored as a memory in the brain and was mostly kept over the break.C. The students' eyes got weaker over the break, which caused the extra error.D. The students learned the form over again in the first minute of the test.

9.

In Session 8, students made only about 2 errors with their eyes closed. Which receptors most likely sent the signals that told their brains where their arms and legs were?

A. Stretch receptors in muscles and jointsB. Light receptors in the eyesC. Taste receptors on the tongueD. Heat receptors in the hands

10.

Use paragraph 2. Sort each task by the receptors whose signals the brain most likely uses most.

11.

Circle each result that is evidence that practice stored the form as a memory.

12.

Valentina's belt test will be in a dim gym on thick, soft mats. Make a claim about how these conditions could affect her one-leg kicks and her form. Give evidence from both tables, and describe the path from sense receptors to the brain to muscles, including the role of memory.