Albert and Bernard just met Cheryl. “When’s your birthday?” Albert asked Cheryl. Cheryl thought a second and said, “I’m not going to tell you, but I’ll give you some clues.” She wrote down a list of 10 dates:
May 15, May 16, May 19 June 17, June 18 July 14, July 16 August 14, August 15, August 17
“My birthday is one of these,” she said. Then Cheryl whispered in Albert’s ear the month and only the month of her birthday. To Bernard, she whispered the day, and only the day. “Can you figure it out now?” she asked Albert.
Albert: I don’t know when your birthday is, but I know Bernard doesn’t know, either.
[Apr 2020, Singapore] Google Meet is used by many teachers to conduct realtime e-learning. However, the experience is very poor when there are ten or more participants. With proper hacks, it can be enjoyable too.
Below is the screenshot after applying the hacks: the teacher’s cam is enlarged on the top left corner and cams of the students are laid out in the alphabetical order of their names (no more random jumping cams); people who are talking are highlighted in cyan.
In Singapore, mathematics syllabus for P1 (primary one) includes addition, subtraction, multiplication, and division. Students work with decimal numbers. Learning about other numeral systems than decimal, they will understand: how a numeral system work in general; why decimal is the default choice.
Scope: learning how binary (base 2), decimal (base 10) and hexadecimal (base 16) systems work starting from 0 to 26; then +5, +10, etc.
Materials: 1) A3 sized paper; 2) snap cubes: 3 colors for each student; 100 pieces per color.
Increment by 1: walking through the number increment procedure with students:
add one piece to the rightmost ‘ones’ column of a number system;
carry over if the total units exceed the current place value – start from the ‘ones’ column till to the right:
snap the all the units of the current column in a straight line and now they form one unit in the preceding column;
Add more than 1: ask students to add 5 or 10 directly:
Snap the cubes to be added and fill the largest place value first – for example, to add 5, one can simply put 4 into the ‘four’ column and 1 into the ‘ones’ column in the base 2 board;