Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 720 · 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.True or false: ironing the paper is a job a child can do. (a) False (b) True
2. 2.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the ink is magnetic (d) the paper ate it
3. 3.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
4. 4.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
5. 5.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) letting the paper dry (c) ironing the paper (d) putting the iron away
6. 6.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
7. 7.🔮 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
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a small bowl (d) yeast
9. 9.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) dipping the cotton bud (d) cutting the lemon
10. 10.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
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.⚖️ 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
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
14. 14.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) cutting the lemon (c) ironing the paper (d) plugging in the iron
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) the same cotton bud (c) the iron setting (d) the kind of juice
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) an adult with an iron (c) white paper (d) a balloon
17. 17.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) wash your hands (d) skip washing
18. 18.🍋 Which of these steps is a job for an adult? (a) writing the message (b) cutting the lemon (c) dipping the cotton bud (d) reading the message
19. 19.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) green (d) blue
20. 20.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
21. 21.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) lemon juice (c) yeast (d) a mirror
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) lemon juice (c) an adult with an iron (d) white paper
23. 23.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) writing the message (d) reading the message
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
25. 25.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) chemical (c) musical (d) physical
26. 26.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
27. 27.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
28. 28.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) an adult with an iron (d) a magnet
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) lemon juice (c) white paper (d) an adult with an iron
30. 30.True or false: reading the message is a job a child can do. (a) True (b) False
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
32. 32.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) the iron is brown (c) heat adds colour (d) paper turns lemony
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) how dark the writing is (c) the same paper (d) the same cotton bud
34. 34.⚖️ 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) False (b) True
35. 35.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) whoever is fastest (d) only an adult
36. 36.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) white paper (c) turmeric powder (d) a balloon
37. 37.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
38. 38.True or false: ironing the paper is a job for an adult. (a) False (b) True
39. 39.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a balloon (c) a cotton bud (d) a mirror
40. 40.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False

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