Most of my experience are with 7th grade math.

1. From Quiz B of the "Moving Staight Ahead"

"The equation 10 = x - 2.5 is a special case of the equation y=mx+b.
Find the slope and y-intercepts for the equation: 10 = x - 2.5"

The solution, "slope=1 and y-intercept=-2.5", comes straight out of theConnected Math Project (CMP) -- a program rated as the best middle school textbook after "rigorously" analysed by AAAS project 2061.

None of the authors (5), reviewers (numerous from AAAS) and 160 teachers who field tested the program realized that 10 = x - 2.5 is a vertical line with no y-intercept and the slope is infinite.

2. This problem is printed on Pg. 29 of "Moving Straight Ahead", 7th grade CMP:

"The 1996 Olympic gold medal winner for the 20-kilometer walk was Jefferson Perez from Ecuador. His time was 1 hour, 20 minutes, 7 seconds.  Perez's time was not good enough to beat the Olympic record set in 1988 by Josef Pribilinec from Czechoslovakia. Prililinec's record for the 20-kilometer was 1 hour, 19 minutes, 57 seconds. What was the walking rate of each person."

My daughter dutifully punched the numbers into her calculator and wrote down the answers as :
Jefferson Perez : 0.00416 km/s
Josef Pribilinec : 0.00417 km/s

Most 7th graders have pretty good concept of speed.  However 0.00416 km/s means nothing to most 7th graders and even some parents. They cannot relate that to their daily experience. If the problem meant to compare the rate of winners, the original description of how long it took a winner to walk 20-kilometer is the most sensible description. Can you imagine a sportscaster announcing that the winner Jefferson Perezs walking rate was 0.00416 km/s as compared to the Olympic
record of 0.00417 km/s achieved by Josef Pribilinec?

On Pg 78, there is a graph plotting the time vs. Altitude for a spaceship.  Obviously the graph is wrong. I cannot think of any "powerful" rockets that can give you infinite acceleration to produce the first extremely steep gain in altitude in the first 2 sec.

The problem with the spaceship graph is the big discrepancy between what the kids see on TV. On TV, the rocket always rises slowly before picking up cceleration, just like a car. Also how can one reach orbit altitude (I assume that is the saturation altitude) in a matter of 2-3 seconds. It is completely unphysical.

4. Bike journal--tooted by the CMP people and reviewers as good learning
Please get some real practise example by real students.

5. Spending hours Drawing Wumps in Stretching and Shrinking

6. Using Chips to do negative number problems. My favorite is solve (-1)x(-1)=+1, as far as most students are concerned, it is magic.

7. Repiles in 7th grade "geometry and similarity" unit.  There is many more efficient ways to teach lengh changes by 2, area changes by 4 (just draw a retangle) then to use these "brain teaser" problems with terms not even appearing in geometry books.

8. 6th grade unit -- Prime Time: Factors and Multiples Kids are required to do posters on perfect numbers. They also learn deficit and abundant numbers. I am not
aware of any real life benefits of learning these numbers except for entertainment.

For more examples in 8th grade, see cmp8