Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 287 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the same cotton bud (c) the kind of juice (d) how dark the writing is
2. 2.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
3. 3.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
4. 4.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) False (b) True
6. 6.True or false: yeast is needed for the secret lemon message. (a) False (b) True
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
8. 8.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) dipping the cotton bud (d) plugging in the iron
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) lemon juice (c) a cotton bud (d) a small bowl
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a battery cell (d) a small bowl
11. 11.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
12. 12.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) white paper (d) turmeric powder
14. 14.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
15. 15.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a battery cell (d) a cotton bud
17. 17.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
18. 18.🔍 Which is the odd one out? (a) reading the message (b) putting the iron away (c) plugging in the iron (d) ironing the paper
19. 19.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) chemical (d) physical
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a magnet (c) a small bowl (d) a cotton bud
21. 21.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) putting the iron away
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the kind of juice (c) the same cotton bud (d) the same paper
23. 23.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
24. 24.🍋 Which of these steps is a job for an adult? (a) reading the message (b) ironing the paper (c) dipping the cotton bud (d) letting the paper dry
25. 25.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
26. 26.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
27. 27.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
28. 28.True or false: white paper is needed for the secret lemon message. (a) False (b) True
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we keep it the same (c) we change it
30. 30.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) lick your fingers (d) skip washing
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
32. 32.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
33. 33.True or false: ironing the paper is a job a child can do. (a) False (b) True
34. 34.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
35. 35.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) plugging in the iron (d) writing the message
36. 36.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
37. 37.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) whoever is fastest (d) only an adult
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the same cotton bud
39. 39.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) reading the message (d) letting the paper dry
40. 40.True or false: a balloon is needed for the secret lemon message. (a) False (b) True

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