Good knots to know are:
Sheet Bend (Required for 2nd class):
The Sheet Bend is commonly used to tie two ropes of unequal thickness together. The blue rope is used to form a bight, and the red rope is passed up through the bight, around the back of the bight, and then tucked under itself.
Bowline (Required for 2nd class):
The Bowline is a commonly used knot to tie a loop in the end of a rope. It has the advantage of not jamming, compared to some other loop forming knots (for example when using an overhand knot on a large bight to form a loop). To tie it, make a small loop in the standing part of the rope. Bring the working end up through the loop, around the rope, and back down into the loop. (You can also remember it this way: the rabbit comes out of the hole, around the tree, and back in the hole.) Then tighten the knot by pulling the standing part of the rope away from the bight.
Two Half-Hitches (Required for Tenderfoot):
This knot is a slip knot, meaning it can slip on the rope in one direction. To tie it, pass the running end of the rope around a pole. Then, bring the end of the rope up and around the standing part of the rope, then back through the loop, creating a half-hitch. Tie another half-hitch outside the loop in the same direction, and you are finished. Just pull the knot snug and slide it against the pole.
Taut Line (Required for Tenderfoot):
An adjustable loop knot for use on lines under tension. It is useful when the length of a line will need to be periodically adjusted in order to maintain tension. To tie it, pass the running end around something to tie it on (ex. a tent stake). Then bring the end over and around the standing part, then back through the loop that formed. Go around the standing part of the loop again (like in two half-hitches), then take the end around the standing part outside the loop, making sure you are going in the same direction, to tie another half-hitch.
Square Knot (Required for Tenderfoot):
The Square Knot is usually learned when we tie the laces on our first pair of shoes. Admittedly it is usually a bow that we tie - but the underlying knot is a Square Knot. We also learn just how unsatisfactory the knot is. It slips, it comes undone, it jams, and it is all too easy to tie a granny instead which behaves even less well. It is intended to be a binding knot and, tied in the right material against a curved surface, the first Half Knot may bind – but it cannot be trusted. To tie it, find the two ends of the rope. Then bring the right end over and under the left end. Then bring the new left end over and under the new right end. Pull the strings extending out of the knot.
Clove Hitch (Required for 1st class):
The Clove Hitch has various applications. For example, in the theater it is used to adjust the height of stage curtains hanging from a bar; and in boating it can be used to initially position a fender hanging from a rail. To tie it, wrap the rope around a pole, then wrap it again, crossing the first wrap, forming an X. On the third wrap, bring the rope under that X.
Figure 8 (Flemish) Knot:
Provides a quick and convenient stopper knot to prevent a line sliding out of sight, e.g., up inside the mast. Its virtue is that, even after it has been jammed tightly against a block, it doesn't bind; it can be undone easily. This virtue is also, occasionally, a vice. The figure 8 can fall undone and then has to be retied.
Over Hand Knot:
The overhand knot can be used as a stopper knot and can keep a rope from fraying or unraveling but the Figure 8 is a much better stopper knot. The Overhand knot is used in other knots including the Square knot which is two Overhand knots. The overhand knot can be used temporarily but can untie very easily if tied around something.
Timber Hitch (Required for 1st class):
The timber hitch is an optimal knot for dragging a log on the ground. It is also the knot that starts a diagonal lashing. To tie it, take the running end around the log, then twist the end around itself at least three times. Tighten the hitch by pulling slack out of the rope.
You might also wrap it this way. Make a bight out of the rope, leaving equal length on both sides. Twist the rope three or more times, then loop it onto the log. Take one end, and loop it through the loop you made to tie the hitch.
Diagonal Lashing (Required for 1st class):
Used to lash two spars together. The Diagonal Lashing secures poles crossing each other at a variety of angles.
To tie it, tie a timber hitch, then, wrap the cord around the poles like the picture shows, creating two sets of wraps. There should be three wraps for each set. Then wrap the cord around the wraps (called fraps) at least three times. Finally, tie a clove hitch on the opposite side of the pole where you tied your clove hitch on.
Square Lashing: (Required for 1st class)
A square lashing is also used to tie two poles together, but at right angles. To tie it, tie a clove hitch around one pole, then tightly wrap the cord around both sticks, going up and around, one pole, then bringing the cord down, being sure to go around the horizontal pole. Repeat this at least two more times. Then, make at least three fraps around the wraps. Tie a clove hitch with the remaining string on the opposite side of the pole you tied your first clove hitch on.
Sheer Lashing (Required for 1st class) & Tripod Lashing:
Sheer and tripod lashings go together because they are used to tied two or more poles parallel to each other. To tie them, start with a clove hitch (like in the square lashing). Then, weave the string over and under the poles 6-10 times, depending on the thickness of the poles and the amount of poles you are wrapping. Then make at least three fraps around the wraps. Finally, tie a clove hitch on the opposite pole from which you tied the first clove hitch on.