Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 432 · 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: plugging in the iron is a job for an adult. (a) True (b) False
2. 2.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
3. 3.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing
4. 4.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
5. 5.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
6. 6.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) letting the paper dry (c) putting the iron away (d) ironing the paper
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
8. 8.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) whoever is fastest (d) any child
9. 9.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) reading the message
10. 10.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) no, it stays brown (d) yes, if shaken
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
12. 12.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) paper turns lemony (d) the juice scorches first
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
14. 14.🍋 Which of these steps is a job a child can do? (a) writing the message (b) ironing the paper (c) putting the iron away (d) cutting the lemon
15. 15.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
16. 16.🧺 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 cotton bud
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) how dark the writing is (c) the iron setting (d) the kind of juice
18. 18.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) blue (d) brown
19. 19.True or false: ironing the paper is a job a child can do. (a) False (b) True
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we measure it (c) we change it
21. 21.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) skip washing (d) lick your fingers
22. 22.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
23. 23.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) dipping the cotton bud (d) reading the message
24. 24.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
25. 25.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) musical (d) chemical
26. 26.⚖️ 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 change it (c) we keep it the same
27. 27.True or false: plugging in the iron is a job a child can do. (a) True (b) False
28. 28.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
29. 29.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) putting the iron away (d) cutting the lemon
30. 30.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
31. 31.⚖️ 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) the iron setting (c) the same cotton bud (d) the kind of juice
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a magnet (c) a small bowl (d) lemon juice
33. 33.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
34. 34.🧺 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 cotton bud (d) a battery cell
35. 35.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) a battery cell (d) an adult with an iron
36. 36.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) turmeric powder (d) yeast
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) the kind of juice (c) how dark the writing is
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
39. 39.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
40. 40.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) it turned into air (d) the paper ate it

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