BERNINA Skillbuilder Sew Along: Blocks 3 & 4

Welcome back to the BERNINA Skillbuilder Sew Along with Sweet Potato Quilts! I’m Christina, quilt pattern designer and your guide through this nine-block sampler series designed to build your quilting skills step by step. If you’re just joining, you can catch up HERE with links to all previous blog posts and free PDF patterns in one place.

In this session, we’re making Block 3 and Block 4. Block 3 focuses on eight-at-a-time half-square triangles, while Block 4 introduces the classic Courthouse Steps block, with a Sawtooth Star in the center. Both blocks will strengthen your accuracy with cutting, piecing, and pressing while expanding your toolbox of essential quilt-making skills.

Download the PDF Pattern for Block 3 here:

Download the PDF Pattern for Block 4 here:

Materials

• Fabric 1–5 and background fabric pieces (yardage requirements and instructions provided in the Pattern Introduction PDF from Week 1)
• Sewing machine: BERNINA 770 QE Plus
• BERNINA Patchwork Foot #37D or Patchwork Foot #97D for precision piecing
• Straight Stitch Plate (recommended for piecing accuracy)
• Acrylic quilting ruler: 6 ½″ x 12 ½″
• Rotary cutter and cutting mat
• Aurifil 50 wt cotton thread
• Wool pressing mat and iron

Skill Highlights

In Block 3, you’ll master eight-at-a-time half-square triangles, a method that lets you make a large number of identical units quickly and efficiently.

Block 4 focuses on the Courthouse Steps block, a close cousin to the Log Cabin. By piecing strips in stair-step order, you’ll test your consistency with seam allowances and practice pressing methods that keep your block square as it grows. This block also features a Sawtooth Star center, giving you more practice with four-at-a-time flying geese and reinforcing your trimming skills to keep points crisp.

Instructions for Block 3: Eight-at-a-Time Half-Square Triangles

Step 1. Prepare Your Squares

Pair two 7″ x 7″ background squares with two 7″ x 7″ Fabric 5 squares. Draw two diagonal lines across the back of each lighter square, then place right sides together with the darker squares.

Step 2. Sew the Units

Sew a ¼″ seam on both sides of each drawn line.
Tip: Chain piecing will speed up the process and keep your stitches consistent.

Step 3. Cut and Press

Cut along the diagonal lines to create four sections, then cut again in the opposite direction. This will yield eight half-square triangles per set. Press seams toward the dark side.

Step 4. Trim to Size

Trim each HST to 3″ x 3″. Align the diagonal seam with the ruler’s diagonal line, ensuring extra fabric extends past the 3″ markings before trimming. Rotate and trim the other two edges for a perfect square.

Step 5. Assemble the Block

Lay out your trimmed HSTs and sew together following the pattern instructions. Your finished block should measure 16 ½″ square unfinished.

Fun Tip: Half-square triangles can be made in one-, two-, four-, or eight-at-a-time methods. Download the Ultimate Half-Square Triangle Guide for sizing charts and instructions that let you make HSTs in any size, any method.

Instructions for Block 4: Courthouse Steps

Step 1. Make the Sawtooth Star

Start with the center Sawtooth Star using four-at-a-time flying geese. Draw diagonal lines on four small squares and pair with one larger square to create flying geese units. Assemble according to the pattern directions for a 4 ½″ x 4 ½″ Sawtooth Star.

Step 2. Add Courthouse Steps Strips

Sew strips to opposite sides of the star center, pressing seams away from the star. Continue building outward in alternating pairs (side, top, side, top) until the block reaches the correct size.

Step 3. Sew with Precision

Use the BERNINA Patchwork Foot #97D with dual-feed engaged. Align the fabric edge with the foot to achieve consistent seam allowances, which is critical for keeping strips straight.

Step 4. Press Carefully

Press seams outward as you go, using up-and-down motions with your iron to avoid stretching strips.

Step 5. Measure and Finish

When complete, your Courthouse Steps block should measure 16 ½″ square unfinished.

Fun Fact: The Courthouse Steps block dates back to the 1800s and was especially popular during the Civil War era. It often symbolized justice or community, while the Log Cabin represented hearth and home.

Want More?

Get the Ultimate Half-Square Triangle Guide free download! This handy sizing chart shows you what size squares to cut for making HSTs in different sizes using one-at-a-time, two-at-a-time, four-at-a-time, and eight-at-a-time methods. It’s a resource you’ll use again and again in your quilting.

Don’t forget to follow along with the video tutorials for extra guidance, and share your progress with #BERNINASkillbuilderSAL in the WeAllSew Community section.

I can’t wait to see your blocks, see you next time! 🧵❤️