Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 113 · 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.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
2. 2.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) it turned into air (d) dry juice is see-through
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is
4. 4.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing stays faint (d) writing turns green
5. 5.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) plugging in the iron (d) reading the message
6. 6.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) writing the message (c) plugging in the iron (d) putting the iron away
7. 7.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) a cotton bud (d) yeast
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) True (b) False
9. 9.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
10. 10.True or false: cutting the lemon is a job a child can do. (a) False (b) True
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
12. 12.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a cotton bud (c) white paper (d) an adult with an iron
14. 14.⚖️ 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) False (b) True
15. 15.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) an adult with an iron (d) a magnet
17. 17.True or false: writing the message is a job a child can do. (a) False (b) True
18. 18.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
19. 19.🔍 Which is the odd one out? (a) cutting the lemon (b) reading the message (c) dipping the cotton bud (d) writing the message
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) white paper (d) a mirror
21. 21.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) only an adult (d) any child
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a balloon (c) lemon juice (d) a cotton bud
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) False (b) True
24. 24.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
25. 25.🛟 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
26. 26.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) physical (d) chemical
27. 27.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
28. 28.⚖️ 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
29. 29.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) plugging in the iron (d) cutting the lemon
30. 30.⚖️ 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 change it (c) we measure it
31. 31.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
32. 32.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
33. 33.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) a magnet (d) a small bowl
34. 34.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) dipping the cotton bud (d) plugging in the iron
35. 35.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) white (d) blue
36. 36.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) letting the paper dry (d) ironing the paper
37. 37.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is cold (d) it is magnetic
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we change it (c) we measure it
39. 39.🔮 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
40. 40.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed

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