Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 923 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) lemon juice (d) turmeric powder
2. 2.⚖️ 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
3. 3.⚖️ 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
4. 4.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
5. 5.🛟 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
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the same cotton bud
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a magnet (c) white paper (d) an adult with an iron
8. 8.⚖️ 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
9. 9.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) dry juice is see-through (d) it turned into air
10. 10.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) blue (c) green (d) brown
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the same cotton bud (c) the kind of juice (d) the same paper
12. 12.⚖️ 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
13. 13.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) reading the message (c) writing the message (d) letting the paper dry
14. 14.True or false: white paper is needed for the secret lemon message. (a) True (b) False
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the iron setting
16. 16.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
17. 17.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
18. 18.⚖️ 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
19. 19.True or false: reading the message is a job a child can do. (a) False (b) True
20. 20.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if cooled (d) yes, if shaken
21. 21.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it can burn skin (d) it is cold
22. 22.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) wash your hands (d) lick your fingers
23. 23.True or false: plugging in the iron is a job for an adult. (a) False (b) True
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
25. 25.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) writing stays faint (d) the paper floats
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) yeast (c) lemon juice (d) a cotton bud
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a cotton bud (c) a balloon (d) yeast
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.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
30. 30.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
31. 31.True or false: putting the iron away is a job a child can do. (a) False (b) True
32. 32.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
33. 33.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
34. 34.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) white paper (c) a mirror (d) turmeric powder
35. 35.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) magnetic (d) musical
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) a battery cell (d) a small bowl
37. 37.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
38. 38.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
39. 39.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) putting the iron away (c) writing the message (d) dipping the cotton bud
40. 40.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed

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