Which of the spinners did not spin properly? Discuss the possible reasons.
Spinners with the toothpick away from the centre and square spinners typically do not spin properly. The main reasons are: (1) When the hole is not at the centre, the spinner is not balanced equally on all sides, causing it to wobble. (2) Square spinners have corners that create uneven weight distribution. (3) If the toothpick length at the bottom is too long or too short, it affects balance. (4) Misalignment between the cardboard and toothpick causes instability during spinning.
Explanation
The chapter explains that the first spinner with a hole at the centre 'appears to be the same from all sides' and 'remains upright and spins'. This indicates that balance and symmetry are crucial for proper spinning. The Teacher's Note suggests that students should try changing factors like 'the length of the toothpick at the bottom of the cardboard, the alignment of the cardboard' to understand what makes spinners work better.