Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 781 · 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) a mirror (b) yeast (c) a cotton bud (d) a balloon
2. 2.⚖️ 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 measure it (c) we keep it the same
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) white paper (d) a magnet
4. 4.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
5. 5.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) reading the message (d) ironing the paper
6. 6.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint
7. 7.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) writing the message (d) putting the iron away
8. 8.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
9. 9.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
10. 10.⚖️ 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 measure it (c) we keep it the same
11. 11.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
12. 12.True or false: putting the iron away is a job for an adult. (a) False (b) True
13. 13.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) dry juice is see-through (d) the ink is magnetic
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) lemon juice (c) white paper (d) a cotton bud
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) white paper (c) an adult with an iron (d) lemon juice
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) True (b) False
18. 18.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) dark brown words (d) almost nothing
19. 19.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) turmeric powder (d) lemon juice
21. 21.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) a cotton bud (d) yeast
23. 23.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a battery cell (c) a small bowl (d) lemon juice
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
26. 26.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
27. 27.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) cutting the lemon (d) dipping the cotton bud
28. 28.🍋 Which of these steps is a job a child can do? (a) writing the message (b) ironing the paper (c) cutting the lemon (d) plugging in the iron
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the kind of juice (c) the iron setting (d) the same paper
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we measure it (c) we keep it the same
33. 33.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) physical (d) musical
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we keep it the same (c) we measure it
36. 36.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
37. 37.🧺 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) a mirror
38. 38.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) white (d) green
39. 39.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
40. 40.True or false: ironing the paper is a job a child can do. (a) True (b) False

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