Beside
Another way through the same lesson.
Lessons
About
Frequently asked questions
Free lessons
High school
9–12
All groups
Elementary
Middle school
High school
American history
1776 is not the Constitution
They treat the Declaration of Independence and the Constitution as the same event, or they think the government we have now started on July 4, 1776.
4 ways ready
American history
The story does not start and end on July 4
They start the founding story on July 4, 1776, and they think the fighting ended that day.
4 ways ready
Algebra
The same move on both sides
They see 2x + 3 = 11 and subtract 3 from only one side, or they treat 2x as 2 plus x.
4 ways ready · a video for you
Chemistry
Change the count, not the substance
They try to balance H2 + O2 → H2O by changing a subscript, so water becomes something else.
4 ways ready · a video for you
Biology
Mitosis keeps the number. Meiosis halves it.
They treat mitosis and meiosis as the same division, or they think every division cuts the chromosome number in half.
4 ways ready · a video for you