Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 947 · 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.⚖️ 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 paper (c) how dark the writing is (d) the kind of juice
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) lemon juice (d) a cotton bud
3. 3.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
4. 4.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) the paper ate it (d) it turned into air
5. 5.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
6. 6.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) green (d) white
7. 7.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
8. 8.True or false: white paper is needed for the secret lemon message. (a) False (b) True
9. 9.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) only an adult (d) any child
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
11. 11.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
12. 12.⚖️ 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
13. 13.🧺 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) a battery cell (d) lemon juice
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) True (b) False
15. 15.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) chemical (d) musical
16. 16.🔍 Which is the odd one out? (a) reading the message (b) plugging in the iron (c) cutting the lemon (d) ironing the paper
17. 17.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) wash your hands (d) rub your eyes
18. 18.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
19. 19.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) a small bowl (d) a magnet
20. 20.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
21. 21.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) white paper (d) a battery cell
22. 22.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
23. 23.⚖️ 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 same paper (d) the kind of juice
24. 24.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
25. 25.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, in the dark (d) yes, if shaken
26. 26.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
27. 27.⚖️ 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
28. 28.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
29. 29.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a battery cell (c) lemon juice (d) yeast
30. 30.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) dipping the cotton bud (c) writing the message (d) reading the message
31. 31.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
33. 33.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
35. 35.⚖️ 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
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) an adult with an iron (d) a mirror
37. 37.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
38. 38.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a mirror (c) an adult with an iron (d) a magnet
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
40. 40.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) writing the message

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