In Science today students completed the "Will it Light?" experiment that we began yesterday afternoon. After testing out each circuit, we discovered that in order for a light bulb to light, we needed to make sure that both the lead tip and the threaded base of the light bulb were connected to the battery. Don't forget the rule about batteries that we learned last week: the negative terminal has to have a clear path (be connected) to the positive terminal. On to circuit diagrams and then open/closed circuits!
Today we reviewed how you can use doubling to solve an unknown multiplication problem:
When attempting to solve the answer to the unknown 8x6, students can using doubling to assist them. Solve 4x6 instead. Or, we can use repeated doubling to solve 2x6 to find 4x6 to find 8x6. Getting confused? I always tell students to draw it out if they are struggling with using doubling as a strategy. Draw an array for 2x6 (2x6 =12). Now, double the array. You now have an array for 4x6 (4x6 = 24 which is twelve doubled; 12+12 = 24). Now, double the array again. You now have an array for 8x6 (8x6 = 48 which is 24 doubled; 24+24 = 48). You can use doubling to help you with your 2x, 4x, and 8x tables because 2+2 = 4 and 4+4 = 8. You can also use doubling for 3x, 6x, and 12x tables (3+3 = 6, 6+6 = 12), and for 5x and 10x (5+5 = 10).
When trying to solve the unknown 48/6, we can solve 48/3 instead (because 3+3 = 6). When we split 48 into 3 equal but separate groups (look at the purple lines), we get 16 in each group; 48/3 = 16. Now, halve this number again to find 48/6; half of 16 is 8; 48/6 = 8. Confused? Use a drawing strategy to help you break 48 into 6 separate but equal groups (look at all the lines). We get 8 in each group; 48/6 = 8. We can also use repeated halving as a strategy:
When trying to solve the unknown 48/8, we can first solve 48/4 (because 4+4 = 8). Or we can solve 48/2 to find 48/4 (because 2+2 = 4), to find 48/8. Confused? Draw it out. We can divide 48 into 2 separate but equal groups; we find 24 in each group. Halve this number to find 48/4; half of 24 is 12; 48/4 = 12. Halve this number to find 48/8; half of 12 is 6; 48/8 = 6. You can see this in the picture (orange squares). When we divide 48 into 8 separate but equal groups, we get 6 in each group; 48/8=6. I always tell students that if they are struggling with doubling or halving they should draw it out. This can be a hard strategy for some students and drawing an array makes it easier to visualize what we are doing. We will continue to work with doubling and halving tomorrow.