Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 843 · 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.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a small bowl (c) a mirror (d) a battery cell
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) lemon juice (d) a mirror
4. 4.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
5. 5.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) musical (c) magnetic (d) physical
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) lemon juice (c) an adult with an iron (d) a small bowl
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we keep it the same (c) we measure it
8. 8.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) blue (d) green
9. 9.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) a magnet (d) a cotton bud
11. 11.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) ironing the paper (d) writing the message
12. 12.⚖️ 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
13. 13.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) it turned into air (d) dry juice is see-through
14. 14.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
15. 15.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) putting the iron away (d) letting the paper dry
16. 16.True or false: putting the iron away is a job a child can do. (a) True (b) False
17. 17.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
18. 18.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) letting the paper dry
19. 19.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) cutting the lemon (d) putting the iron away
20. 20.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing stays faint (d) writing turns green
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) how dark the writing is (c) the kind of juice (d) the iron setting
22. 22.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
23. 23.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
24. 24.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) plugging in the iron (d) dipping the cotton bud
25. 25.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) a rainbow (d) almost nothing
26. 26.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) letting the paper dry (c) writing the message (d) dipping the cotton bud
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) a small bowl (c) an adult with an iron (d) lemon juice
28. 28.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
30. 30.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a battery cell (c) a small bowl (d) white paper
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a cotton bud (d) yeast
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) how dark the writing is (c) the ironing time (d) the kind of juice
34. 34.True or false: white paper is needed for the secret lemon message. (a) False (b) True
35. 35.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) a cotton bud (d) turmeric powder
37. 37.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
38. 38.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) writing the message (d) cutting the lemon
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a balloon (c) an adult with an iron (d) white paper
40. 40.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it

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