If you are looking for video tutorials for your students to use to reinforce concepts, or even explore new concepts, Khan Academy has TONS of videos for science (and math) and they are FREE.
For example, here is a detailed video about Mitosis, Meiosis, and Sexual Reproduction:
The homepage is: http://www.khanacademy.org/
To introduce the triple beam balance (tbb), I had the students complete a tbb tutorial where they learned how to find the mass by reading the riders on the 100′s, 10′s, and 1′s beams and how to combine those values into a single value.
My expectations were for them to read the mass to the nearest 10th, but if they wanted to guess the 100ths place, they could attempt that as well. The students caught on very quickly and some were really proud of themselves if they guessed the 100ths place exactly. In the past, when I introduced the tbb and didn’t use the tutorial, most students had trouble reading the ones beam and the 10ths place value. Completing the tbb tutorial really increased the students’ accuracy in reading the measurements on the beams and very few, if any students, asked for help when they used a real tbb and had to record the masses.
Another thing I really like about this tutorial, is that the students have immediate feedback as to if their answer was correct or not. If their answers were incorrect, they could compare their answer to the correct answer and reflect about it, figure out what they did differently, and how they can correct it for the next problem.
After completing the tbb tutorial, I introduced the real tbb with a demonstration on how to use it correctly and how to find the mass of an unknown object. I also emphasized that the riders have to click into the notches for the 100s or 10s beam, otherwise its not that exact value, its somewhere in between two adjacent values. We also discussed the proper way to hold, carry, and take care of a tbb. When the tbb is not in use, my mantra is “Riders to Right“. Moving the riders to the right reduces the bouncing of the beams when they are being transported or not in use.
Each lab table had a group of random items from the science room and they had to find the masses of whatever they liked, and however they wanted to group the items. For example, the could stack 3 blocks onto the pan and find the combined mass of those items. They could do a single item such as a penny, too.
pg. 30 – Reading a Triple Beam Balance – Laptop Activity Link
pg. 31 – Vocab: TBB Balance
pg. 32 – TBB Mass Lab
pg. 33 - TBB Analysis – Answer questions #1-5 and write a conclusion