small fixes

app/lessons/unit-1-fractions/divide/page.tsx

@@ -16,7 +16,7 @@ export default function DividePage() {
 
       <h1 className="text-3xl font-bold tracking-tight">Divide Fractions</h1>
 
-      <FractionOperationExplorer />
+      <FractionOperationExplorer initialOperation="divide" />
     </div>
   );
 }

app/lessons/unit-1-fractions/multiply/page.tsx

@@ -16,7 +16,7 @@ export default function MultiplyPage() {
 
       <h1 className="text-3xl font-bold tracking-tight">Multiply Fractions</h1>
 
-      <FractionOperationExplorer />
+      <FractionOperationExplorer initialOperation="multiply" />
     </div>
   );
 }

app/lessons/unit-1-fractions/whole-from-fractions/page.tsx

@@ -16,7 +16,7 @@ export default function WholeFromFractionsPage() {
 
       <h1 className="text-3xl font-bold tracking-tight">Calculate the Whole from Fractions</h1>
 
-      <FractionQuantityExplorer />
+      <FractionQuantityExplorer initialMode="findWhole" />
     </div>
   );
 }

app/lessons/unit-3-decimal-operations/multiply-divide/page.tsx

@@ -16,7 +16,7 @@ export default function MultiplyDividePage() {
 
       <h1 className="text-3xl font-bold tracking-tight">Multiply and Divide Decimals</h1>
 
-      <DecimalArithmeticExplorer />
+      <DecimalArithmeticExplorer initialOperation="multiply" />
     </div>
   );
 }

app/lessons/unit-4-ratio-proportion/simplify-ratios/page.tsx

@@ -16,7 +16,7 @@ export default function SimplifyRatiosPage() {
 
       <h1 className="text-3xl font-bold tracking-tight">Simplify Ratios</h1>
 
-      <RatioExplorer />
+      <RatioExplorer initialMode="simplify" />
     </div>
   );
 }

app/practice/page.tsx

@@ -117,7 +117,15 @@ export default function PracticePage() {
                   hover
                   className="cursor-pointer"
                   accent={topic.unitColor}
+                  tabIndex={0}
+                  role="button"
                   onClick={() => setSelectedTopic(topic)}
+                  onKeyDown={(e) => {
+                    if (e.key === "Enter" || e.key === " ") {
+                      e.preventDefault();
+                      setSelectedTopic(topic);
+                    }
+                  }}
                 >
                   <div className="flex items-center justify-between">
                     <span className="font-bold">{topic.label}</span>